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  • CLASSES

    Other Agents used in HIV

    DEA CLASS

    Rx

    DESCRIPTION

    A CYP3A inhibitor
    Used as a booster to increase exposure of atazanavir or darunavir in adults and pediatric patients with HIV (weight dependent)
    Monitor closely for drug interactions

    COMMON BRAND NAMES

    TYBOST

    HOW SUPPLIED

    TYBOST Oral Tab: 150mg

    DOSAGE & INDICATIONS

    For use as a pharmacokinetic enhancer (booster) during the treatment of human immunodeficiency virus (HIV) infection.
    To increase the systemic exposure of atazanavir.
    Oral dosage
    Adults

    150 mg PO once daily with atazanavir 300 mg PO once daily in combination with other antiretroviral agents. Do not coadminister with another protease inhibitor (including boosting doses of ritonavir), elvitegravir, or etravirine. In addition, antiretroviral-experienced patients should also avoid concurrent use of cobicistat and atazanavir with efavirenz.[58000]

    Children and Adolescents weighing 35 kg or more

    150 mg PO once daily with atazanavir 300 mg PO once daily in combination with other antiretroviral agents. Do not coadminister with another protease inhibitor (including boosting doses of ritonavir), elvitegravir, or etravirine. In addition, antiretroviral-experienced patients should also avoid concurrent use of cobicistat and atazanavir with efavirenz.[58000]

    To increase the systemic exposure of darunavir in patients with no darunavir resistance-associated substitutions.
    Oral dosage
    Adults

    150 mg PO once daily with darunavir 800 mg PO once daily in combination with other antiretroviral agents. Do not coadminister with another protease inhibitor (including boosting doses of ritonavir), elvitegravir, etravirine, efavirenz, or nevirapine.

    Children and Adolescents weighing 40 kg or more

    150 mg PO once daily with darunavir 800 mg PO once daily in combination with other antiretroviral agents. Do not coadminister with another protease inhibitor (including boosting doses of ritonavir), elvitegravir, etravirine, efavirenz, or nevirapine.

    MAXIMUM DOSAGE

    Adults

    150 mg/day PO.

    Geriatric

    150 mg/day PO.

    Adolescents

    weight 35 kg or more: 150 mg/day PO.
    weight less than 35 kg: Safety and efficacy have not been established.

    Children

    weight 35 kg or more: 150 mg/day PO.
    weight less than 35 kg: Safety and efficacy have not been established.

    Infants

    Safety and efficacy have not been established.

    Neonates

    Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    No dosage adjustment is necessary for patients with mild to moderate hepatic impairment (Child-Pugh A or B). Caution is advised if used in patients with severe hepatic impairment (Child-Pugh C), as studies have not been conducted in this population.

    Renal Impairment

    Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

    ADMINISTRATION

    Oral Administration
    Oral Solid Formulations

    Administer concurrently (at the same time) as atazanavir or darunavir.
    Administer tablets with food.

    STORAGE

    TYBOST:
    - Store and dispense in original container
    - Store at 77 degrees F; excursions permitted to 59-86 degrees F

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

    Cobicistat is an inhibitor and substrate for CYP3A and may inhibit the clearance of certain medications. Thus, use is contraindicated with medications that undergo CYP3A metabolism and are associated with serious or life-threatening adverse events. This drug, when used in combination with atazanavir or darunavir, is also contraindicated for use with strong CYP3A inducers (i.e., rifampin, St. John's wort); concurrent use of strong CYP3A inducers can lead to a marked decrease in plasma concentrations of cobicistat and both protease inhibitors, which may result in loss of therapeutic effect and viral resistance. Consider the potential for drug interactions prior to and during therapy with cobicistat; additional monitoring for efficacy and adverse reactions may be needed.[58000]
     
    Unplanned antiretroviral therapy interruption may be necessary for specific situations, such as serious drug toxicity, intercurrent illness or surgery precluding oral intake (e.g., gastroenteritis or pancreatitis), severe hyperemesis gravidarum unresponsive to antiemetics, or drug non-availability. If short-term treatment interruption is necessary, in general it is recommended that all antiretroviral agents be discontinued simultaneously, especially if the interruption is because of serious toxicity. However, if a short-term treatment interruption is anticipated in the case of elective surgery, the pharmacokinetic properties and food requirements of specific drugs should be considered. When the antiretroviral regimen contains drugs with differing half-lives, stopping all drugs simultaneously may result in functional monotherapy of the drug with the longest half-life. For example, after discontinuation, the duration of detectable drug concentrations of efavirenz and nevirapine range from less than 1 week to more than 3 weeks. Simultaneously stopping all drugs in a regimen containing these agents may result in functional monotherapy with the NNRTI and may increase the risk of NNRTI-resistant mutations. Planned treatment discontinuation has been suggested as a strategy in certain situations, such as to reduce costs and long-term toxicity in patients who achieve viral suppression or to allow reversion to wild-type virus in patients who experience treatment failure. While research is ongoing, no approaches can be recommended outside of controlled clinical trials; data currently do not support planned treatment interruptions. In particular, treatment interruption is not recommended in patients who have few treatment options available (i.e., exposure to multiple antiretroviral agents, antiretroviral treatment failure, or extensive resistance mutations) unless done in a clinical trial setting. Several clinical trials, yielding conflicting results, have been conducted to better understand the role of treatment interruption in these patients.[42452] [46638]

    Hypophosphatemia, renal disease, renal failure, renal impairment

    Cobicistat decreases estimated creatinine clearance by inhibiting tubular section without affecting glomerular function; therefore, an estimated creatinine clearance (CrCl) should be assessed in all patients prior to and during treatment. Because dosage adjustments are not available for cobicistat, an alternative medication should be considered in patients found to have renal impairment. In addition, use of cobicistat in combination with tenofovir disoproxil fumarate should be avoided in patients with a CrCl less than 70 mL/min at baseline because tenofovir is eliminated by a combination of glomerular filtration and active renal tubular secretion. When considering treatment with a regimen that includes both cobicistat and tenofovir, obtain a baseline estimated CrCl, urine glucose, and urine protein prior to initiating therapy. An estimated CrCl, urine glucose, and urine protein should also be performed during therapy as clinically appropriate. Patients who experience a serum creatinine increase of greater than 0.4 mg/dL from baseline should be more closely monitored. Further, monitoring of serum phosphate concentrations is advised for patients with chronic renal disease. If the CrCl falls below 50 mL/min, discontinue treatment as dose adjustments have not been established for tenofovir when used with cobicistat. During clinical trials, the combination of cobicistat and tenofovir was associated with renal impairment, including acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia). During the 144 week study period, 10 patients (2.9%) discontinued treatment due to renal adverse effects, with 7 of the 10 patients (2% overall) having laboratory finding suggestive of proximal renal tubulopathy. One of the 10 had renal impairment (CrCl less than 70 mL/min) at baseline. Manifestations of proximal renal tubulopathy may include persistent or worsening bone pain, pain in extremities, bone fractures, or muscle pain and weakness; closely evaluate the renal function of patients who experience these symptoms while receiving cobicistat and tenofovir. Avoid administering concurrently with or recently after a nephrotoxic agent, including high-dose or multiple non-steroidal antiinflammatory drugs (NSAIDS), as this may increase the risk for renal adverse effects.[58000]

    Hepatic disease

    Studies evaluating the safety and pharmacokinetics of cobicistat in patients with severe hepatic disease (Child-Pugh Class C) have not been conducted; caution is advised if used in this patient population. The drug may be used without dose adjustments in patients with mild to moderate hepatic dysfunction (Child-Pugh Class A and B).

    Pregnancy

    Antiretroviral therapy should be provided to all women during pregnancy, regardless of HIV RNA concentrations or CD4 cell count. Using highly active antiretroviral combination therapy (HAART) to maximally suppress viral replication is the most effective strategy to prevent the development of resistance and to minimize the risk of perinatal transmission. In treatment-naive women, begin HAART as soon as pregnancy is recognized or HIV is diagnosed, without waiting for the results of resistance testing; subsequent modifications to the treatment regimen should be made once the test results are available. Women who are currently receiving antiretroviral treatment when pregnancy is recognized should continue their treatment regimen if it is currently effective in suppressing viral replication; consider resistance testing if HIV RNA concentrations are more than 500 copies/mL. For women not currently receiving HAART, but who have previously received treatment, obtain a complete and accurate history of all prior antiretroviral regimens used and results of prior resistance testing, and perform resistance testing if HIV RNA concentrations are more than 500 copies/mL; treatment should be initiated prior to receiving resistance test results. Cobicistat-containing regimens are not recommended for use as initial therapies in pregnant women or women who are trying to conceive, as inadequate cobicistat concentrations and viral breakthroughs have been reported during the second and third trimesters. Consider the use of more effective antiretroviral regimens. If a cobicistat-containing regimen is used during pregnancy, frequently monitor viral loads (i.e., every 1 to 2 months). Data from the Antiretroviral Pregnancy Registry (APR), which includes more than 400 first trimester exposures to cobicistat, have shown no significant difference in the risk of overall major birth defects when compared to the 2.7% background rate among pregnant women in the US. When exposure occurred in the first trimester, the prevalence of defects was 3.9% (95% CI: 2.3 to 6.3). Regular laboratory monitoring is recommended to determine antiretroviral efficacy. Monitor CD4 counts at the initial visit. Women who have been on HAART for at least 2 years and have consistent viral suppression and CD4 counts consistently greater than 300 cells/mm3 do not need CD4 counts monitored after the initial visit during the pregnancy. However, CD4 counts should be monitored every 3 months during pregnancy for women on HAART less than 2 years, women with CD4 count less than 300 cells/mm3, or women with inconsistent adherence or detectable viral loads. Monitor plasma HIV RNA at the initial visit, 2 to 4 weeks after initiating or changing therapy, monthly until undetectable, then at least every 3 months, and at 34 to 36 weeks gestation. Perform antiretroviral resistance assay (genotypic testing, and if indicated, phenotypic testing) at baseline in all women with HIV RNA concentrations more than 500 copies/mL, unless they have already been tested for resistance. A first trimester ultrasound is recommended to confirm gestational age and provide an accurate estimation of gestational age at delivery. A second trimester ultrasound can be used for both anatomical survey and determination of gestational age in those patients not seen until later in gestation. Perform standard glucose screening in women receiving antiretroviral therapy at 24 to 28 weeks gestation, although it should be noted that some experts would perform earlier screening with ongoing chronic protease inhibitor-based therapy initiated prior to pregnancy, similar to recommendations for women with high-risk factors for glucose intolerance. Liver function testing is recommended within 2 to 4 weeks after initiating or changing antiretroviral therapy, and approximately every 3 months thereafter during pregnancy (or as needed). All pregnant women should be counseled about the importance of adherence to their antiretroviral regimen to reduce the potential for the development of resistance and perinatal transmission. It is strongly recommended that antiretroviral therapy, once initiated, not be discontinued. If a woman decides to discontinue therapy, a consultation with an HIV specialist is recommended. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to cobicistat; information about the registry can be obtained at www.apregistry.com or by calling 1-800-258-4263.[27468] [23512] [58000]

    Breast-feeding

    To reduce the risk of postnatal transmission, mothers with HIV within the United States are advised by the Centers for Disease Control and Prevention to avoid breast-feeding. This recommendation applies to both untreated women and women who are receiving antiretroviral therapy, including regimens containing cobicistat. If a mother with HIV opts to breast-feed, the infant should undergo immediate diagnostic and virologic HIV testing. Testing should continue throughout breast-feeding and up to 6 months after cessation of breast-feeding. For expert consultation, health care workers may contact the Perinatal HIV Hotline (888-448-8765).[42452] It is unknown if cobicistat is present in human milk. Antiretroviral drugs whose passage into human breast milk have been evaluated include tenofovir, emtricitabine, nevirapine, zidovudine, lamivudine, and nelfinavir.

    Human immunodeficiency virus (HIV) infection resistance

    Testing for human immunodeficiency virus (HIV) infection resistance is recommended in all antiretroviral treatment-naive patients at the time of HIV diagnosis, regardless of whether treatment will be initiated. Additionally, perform resistance testing prior to initiating or changing any HIV treatment regimen, including those containing cobicistat. Transmission of drug-resistant HIV strains has been both well documented and associated with suboptimal virologic response to initial antiretroviral therapy. In high-income countries (e.g., US, some European countries, Australia, Japan), approximately 10% to 17% of treatment-naive individuals have resistance mutations to at least 1 antiretroviral drug; up to 8% (but generally less than 5%) of transmitted viruses will exhibit resistance to drugs from more than 1 class. Therefore, resistance testing at baseline can help optimize treatment and, thus, virologic response. In the absence of therapy, resistant viruses may decline over time to less than the detection limit of standard resistance tests, but may still increase the risk of treatment failure when therapy is eventually initiated. Thus, if therapy is deferred, resistance testing should still be performed during acute HIV infection with the genotypic resistance test result kept in the patient's medical record until it becomes clinically useful. Additionally, because of the possibility of acquisition of another drug-resistant virus before treatment initiation, repeat resistance testing at the time therapy is initiated would be prudent. Emtricitabine will not likely be effective in individuals who display resistance to lamivudine, due to the similarities between the two drugs. Clinicians should not expect patients with the M184 mutation associated with lamivudine to benefit from an emtricitabine containing regimen. The M184 mutation confers high-level resistance, and emtricitabine, like lamivudine, selects for the M184 mutation. It is important that persons with detectable viral load who plan to switch therapy from lamivudine to emtricitabine have genotypic testing performed to determine whether the M184V mutation is present. A patient's treatment history is also extremely important; if lamivudine has failed in the past, the 184 is archived, thus rendering emtricitabine ineffective in this patient population.

    ADVERSE REACTIONS

    Severe

    Fanconi syndrome / Delayed / 0-2.0
    rhabdomyolysis / Delayed / 0-2.0
    renal failure (unspecified) / Delayed / Incidence not known

    Moderate

    hyperbilirubinemia / Delayed / 73.0-73.0
    hematuria / Delayed / 6.0-6.0
    elevated hepatic enzymes / Delayed / 4.0-6.0
    jaundice / Delayed / 6.0-6.0
    hyperamylasemia / Delayed / 4.0-4.0
    glycosuria / Early / 3.0-3.0
    neutropenia / Delayed / 3.0-3.0
    nephrolithiasis / Delayed / 0-2.0
    depression / Delayed / 0-2.0
    hyperglycemia / Delayed / 2.0-2.0
    hypophosphatemia / Delayed / Incidence not known
    hypercholesterolemia / Delayed / Incidence not known
    hypertriglyceridemia / Delayed / Incidence not known

    Mild

    rash / Early / 5.0-5.0
    vomiting / Early / 0-2.0
    diarrhea / Early / 2.0-2.0
    nausea / Early / 2.0-2.0
    abdominal pain / Early / 0-2.0
    fatigue / Early / 0-2.0
    headache / Early / 2.0-2.0
    insomnia / Early / 0-2.0
    maculopapular rash / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    pruritus / Rapid / Incidence not known
    folliculitis / Delayed / Incidence not known

    DRUG INTERACTIONS

    Abacavir; Dolutegravir; Lamivudine: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
    Abemaciclib: (Major) If coadministration with cobicistat is necessary, reduce the dose of abemaciclib to 100 mg PO twice daily in patients on either of the recommended starting doses of either 200 mg or 150 mg twice daily. In patients who have had already had a dose reduction to 100 mg twice daily due to adverse reactions, further reduce the dose of abemaciclib to 50 mg PO twice daily. Discontinue abemaciclib for patients unable to tolerate 50 mg twice daily. If cobicistat is discontinued, increase the dose of abemaciclib to the original dose after 3 to 5 half-lives of cobicistat. Abemaciclib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the relative potency adjusted unbound AUC of abemaciclib plus its active metabolites (M2, M18, and M20) by 2.5-fold in cancer patients.
    Acalabrutinib: (Major) Avoid the concomitant use of acalabrutinib and cobicistat; significantly increased acalabrutinib exposure may occur. Acalabrutinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In healthy subjects, the Cmax and AUC values of acalabrutinib were increased by 3.9-fold and 5.1-fold, respectively, when acalabrutinib was coadministered with another strong inhibitor for 5 days.
    Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
    Acetaminophen; Chlorpheniramine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Acetaminophen; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Acetaminophen; Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Acetaminophen; Diphenhydramine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Acetaminophen; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Acetaminophen; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
    Ado-Trastuzumab emtansine: (Major) Avoid coadministration of cobicistat with ado-trastuzumab emtansine if possible due to the risk of elevated exposure to the cytotoxic component of ado-trastuzumab emtansine, DM1. Delay ado-trastuzumab emtansine treatment until cobicistat has cleared from the circulation (approximately 3 half-lives of cobicistat) when possible. If concomitant use is unavoidable, closely monitor patients for ado-trastuzumab emtansine-related adverse reactions. The cytotoxic component of ado-trastuzumab emtansine, DM1, is metabolized mainly by CYP3A4 and to a lesser extent by CYP3A5; cobicistat is a strong CYP3A4 inhibitor. Formal drug interaction studies with ado-trastuzumab emtansine have not been conducted.
    Afatinib: (Moderate) If the concomitant use of cobicistat and afatinib is necessary, monitor for afatinib-related adverse reactions. If the original dose of afatinib is not tolerated, consider reducing the daily dose of afatinib by 10 mg; resume the previous dose of afatinib as tolerated after discontinuation of cobicistat. The manufacturer of afatinib recommends permanent discontinuation of therapy for severe or intolerant adverse drug reactions at a dose of 20 mg per day, but does not address a minimum dose otherwise. Afatinib is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor; coadministration may increase plasma concentrations of afatinib. Administration with another P-gp inhibitor, given 1 hour before a single dose of afatinib, increased afatinib exposure by 48%; there was no change in afatinib exposure when the P-gp inhibitor was administered at the same time as afatinib or 6 hours later. In healthy subjects, the relative bioavailability for AUC and Cmax of afatinib was 119% and 104%, respectively, when coadministered with the same P-gp inhibitor, and 111% and 105% when the inhibitor was administered 6 hours after afatinib.
    Aldesleukin, IL-2: (Moderate) Caution is warranted when cobicistat is administered with aldesleukin, IL-2 as there is a potential for elevated cobicistat concentrations. Aldesleukin, IL-2 is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4.
    Alfentanil: (Moderate) The plasma concentrations of alfentanil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hypotension, nausea, itching, and respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor and alfentanil is a CYP3A4 substrate.
    Alfuzosin: (Contraindicated) Alfuzosin is contraindicated for use with cobicistat due to the potential for serious/life-threatening reactions, including hypotension. Coadministration is expected to reduce the metabolism and increase systemic exposure to alfuzosin. Alfuzosin is primarily metabolized by CYP3A4; cobicistat is a strong inhibitor of this enzyme. Coadministration of another strong CYP3A4 inhibitor increased the alfuzosin AUC by 2.5-fold to 3.2-fold.
    Aliskiren: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
    Aliskiren; Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate.
    Aliskiren; Valsartan: (Moderate) The plasma concentrations of aliskiren may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as decreased blood pressure, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor and aliskiren is a CYP3A4 and P-gp substrate. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Almotriptan: (Moderate) The maximum recommended starting dose of almotriptan is 6.25 mg if coadministration with cobicistat is necessary; do not exceed 12.5 mg within a 24-hour period. Concomitant use of almotriptan and cobicistat should be avoided in patients with renal or hepatic impairment. Almotriptan is a CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased almotriptan exposure by approximately 60%.
    Alogliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Alosetron: (Moderate) Concomitant use of alosetron with cobicistat may result in increased serum concentrations of alosetron and increase the risk for adverse reactions. Caution and close monitoring are advised if these drugs are used together. Alosetron is a substrate of hepatic isoenzyme CYP3A4; cobicistat is a strong inhibitor of this enzyme. In a study of healthy female subjects, another strong CYP3A4 inhibitor increased mean alosetron AUC by 29%.
    Alpelisib: (Major) Avoid coadministration of alpelisib with cobicistat due to increased exposure to alpelisib and the risk of alpelisib-related toxicity. If concomitant use is unavoidable, closely monitor for alpelisib-related adverse reactions. Alpelisib is a BCRP substrate and cobicistat is a BCRP inhibitor.
    Alprazolam: (Contraindicated) Coadministration of cobicistat and alprazolam is contraindicated due to the potential for elevated alprazolam concentrations, which may cause prolonged sedation and respiratory depression. Lorazepam, oxazepam, or temazepam may be safer alternatives if a benzodiazepine must be administered in combination with cobicistat, as these benzodiazepines are not oxidatively metabolized. Alprazolam is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased alprazolam exposure by 2.7- to 3.98-fold.
    Amiodarone: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of amiodarone with cobicistat. Amiodarone is a substrate and inhibitor of CYP3A4 and an inhibitor CYP2D6, cobicistat is a substrate and strong inhibitor of CYP3A and CYP2D6. Concurrent use may result in elevated concentration of both drugs.
    Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Amlodipine; Atorvastatin: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold. (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Amlodipine; Benazepril: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Amlodipine; Celecoxib: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Amlodipine; Olmesartan: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Amlodipine; Valsartan: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Amoxicillin; Clarithromycin; Omeprazole: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
    Apalutamide: (Major) Coadministration of cobicistat with apalutamide is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. In addition, there is a potential for increased apalutamide exposure. If these drugs are used together, monitor for an increase in apalutamide-related adverse reactions. Consider reducing the dose of apalutamide if necessary based on tolerability in patients experiencing grade 3 or higher adverse reactions or intolerable toxicities. Apalutamide is a substrate and strong inducer of CYP3A4. Cobicstat is a substrate and strong inhibitor of CYP3A4. Coadministration with one strong CYP3A4 inhibitor decreased the Cmax of single-dose apalutamide by 22% and the AUC remained similar. Concomitant use with another strong CYP3A4 inhibitor is predicted to increase the single-dose apalutamide AUC by 24% but have no effect on Cmax; the steady-state Cmax and AUC are predicted to increase by 38% and 51%, respectively. The steady-state exposure of the active moieties (unbound apalutamide plus potency-adjusted unbound N-desmethyl apalutamide) is predicted to increase by 28%.
    Apixaban: (Major) Reduce the apixaban dose by 50% when coadministered with drugs that are both strong inhibitors of CYP3A4 and P-gp, such as cobicistat containing medications. If patients are already receiving 2.5 mg twice daily, avoid concomitant administration. Concomitant administration results in increased exposure to apixaban and an increase in the risk of bleeding.
    Aprepitant, Fosaprepitant: (Major) Avoid the concomitant use due to substantially increased exposure of aprepitant; increased cobicistat exposure may also occur. If coadministration cannot be avoided, use caution and monitor for an increase in cobicistat- and aprepitant-related adverse effects for several days after administration of a multi-day aprepitant regimen. After administration, fosaprepitant is rapidly converted to aprepitant and shares the same drug interactions. Cobicistat is a strong CYP3A4 inhibitor and aprepitant is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased the AUC of aprepitant by approximately 5-fold, and the mean terminal half-life by approximately 3-fold. Cobicistat is also a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor. When administered as a single oral or single intravenous dose, the inhibitory effect of aprepitant on CYP3A4 is weak and did not result in a clinically significant increase in the AUC of a sensitive substrate.
    Aripiprazole: (Major) The plasma concentrations of aripiprazole, a CYP3A4 and CYP2D6 substrate, may be elevated when administered concurrently with cobicistat, a CYP2D6 inhibitor and strong CYP3A4 inhibitor. The manufacturer of aripiprazole recommends that patients receiving a combination of a CYP3A4 and CYP2D6 inhibitor should have their oral aripiprazole dose reduced to one-quarter (25%) of the usual dose with subsequent adjustments based upon clinical response. Adults receiving a combination of a CYP3A4 and CYP2D6 inhibitor for more than 14 days should have their Abilify Maintena dose reduced from 400 mg/month to 200 mg/month or from 300 mg/month to 160 mg/month, respectively. In adults receiving Aristada, the Aristada dose should be reduced to the next lower strength during use of a strong CYP3A4 inhibitor, such as cobicistat, for more than 14 days. For patients receiving 882 mg of Aristada every 6 weeks or 1,064 mg every 2 months, the next lower strength should be 441 mg administered every 4 weeks. No dosage adjustment is necessary in patients taking 441 mg IM of Aristada, if tolerated. In adults receiving Aristada 662 mg, 882 mg, or 1,064 mg, combined use of a strong CYP2D6 inhibitor and a strong CYP3A4 inhibitor for more than 14 days should be avoided; no dose adjustment is needed in patients taking 441 mg, if tolerated. Avoid concurrent use of Aristada Initio and strong CYP3A4 inhibitors because the dose of Aristada Initio cannot be modified.
    Armodafinil: (Major) Coadministration of cobicistat with armodafinil is not recommended as there is a potential for elevated armodafinil concentrations and decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Armodafinil is a CYP3A4 substrate/inducer and a P-glycoprotein (P-gp) substrate. Cobicistat is an inhibitor of CYP3A4 and P-gp, and a substrate of CYP3A4.
    Artemether; Lumefantrine: (Moderate) Caution is warranted when cobicistat with artemether; lumefantrine as there is a potential for elevated artemether, lumefantrine, and cobicistat concentrations. Both artemether and lumefantrine are CYP3A4 substrate and lumefantrine is CYP2D6 inhibitor. Cobicistat is a strong inhibitor of CYP3A4 and a substrate of CYP2D6. Coadministration with another strong CYP3A4 inhibitor increased lumefantrine exposure by 1.6-fold. (Moderate) Caution is warranted when cobicistat with artemether; lumefantrine as there is a potential for elevated artemether, lumefantrine, and cobicistat concentrations. Both artemether and lumefantrine are CYP3A4 substrates and lumefantrine is CYP2D6 inhibitor. Cobicistat is a strong inhibitor of CYP3A4 and a substrate of CYP2D6. In a drug interaction study, administration of a strong CYP3A4 inhibitor, resulted in a moderate increase in exposure to artemether, DHA, and lumefantrine.
    Asciminib: (Moderate) Closely monitor for asciminib-related adverse reactions if concurrent use of asciminib 200 mg twice daily with cobicistat is necessary as asciminib exposure may increase. Asciminib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
    Asenapine: (Moderate) Caution is warranted when cobicistat is administered with asenapine as there is a potential for increased aspenapine concentrations. Asenapine is a substrate of CYP3A4 and CYP2D6. Cobicistat is an inhibitor of CYP3A4 and CYP2D6.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
    Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Aspirin, ASA; Omeprazole: (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
    Aspirin, ASA; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
    Aspirin, ASA; Pravastatin: (Major) The plasma concentrations of pravastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or GI effects, is recommended during coadministration. Cobicistat is a organic anion transporting polypeptide (OATP) inhibitor, while pravastatin is a OATP1B1 substrate.
    Atogepant: (Major) Limit the dose of atogepant to 10 mg PO once daily if coadministered with cobicistat. Concurrent use may increase atogepant exposure and the risk of adverse effects. Atogepant is a substrate of CYP3A, OATP1B1, and OATP1B3 and cobicistat is a strong CYP3A inhibitor and OATP inhibitor. Coadministration with a strong CYP3A inhibitor and OATP inhibitor resulted in a 5.5-fold and 2.85-fold increase in atogepant exposure, respectively, and a 2.15-fold and 2.23-fold increase in atogepant peak concentration, respectively.
    Atomoxetine: (Moderate) The plasma concentrations of atomoxetine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as dizziness, drowsiness, hypertension, and other cardiac adverse events, is recommended during coadministration and dosage adjustments for atomoxetine may be warranted. Cobicistat is a CYP2D6 inhibitor and atomoxetine is a CYP2D6 substrate.
    Atorvastatin: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold.
    Atorvastatin; Ezetimibe: (Major) When administering atorvastatin concurrently with cobicistat, use the lowest starting dose of atorvastatin and carefully titrate while monitoring for adverse events (myopathy); DO NOT exceed a maximum daily atorvastatin dose of 20 mg daily. Cobicistat is a strong CYP3A4 inhibitor and atorvastatin is a CYP3A4 substrate. Coadministration with other strong CYP3A4 inhibitors increased atorvastatin exposure by 3.3- to 4.4-fold.
    Avacopan: (Major) Reduce the dose of avacopan to 30 mg once daily if concomitant use of cobicistat is necessary. Concomitant use may increase avacopan exposure and risk for avacopan-related adverse effects. Avacopan is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Concomitant use of another strong CYP3A inhibitor increased avacopan overall exposure 2.19-fold.
    Avanafil: (Major) Do not use avanafil in patients receiving cobicistat due to the risk for increased avanafil serum concentrations and serious adverse reactions. Avanafil is a sensitive CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the avanafil AUC by 13-fold.
    Avapritinib: (Major) Avoid coadministration of avapritinib with cobicistat due to the risk of increased avapritinib-related adverse reactions. Avapritinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor is predicted to increase the AUC of avapritinib by 600% at steady-state.
    Axitinib: (Major) Avoid coadministration of axitinib with cobicistat due to the risk of increased axitinib-related adverse reactions. If coadministration is unavoidable, decrease the dose of axitinib by approximately half; subsequent doses can be increased or decreased based on individual safety and tolerability. Resume the original dose of axitinib approximately 3 to 5 half-lives after cobicistat is discontinued. Axitinib is a CYP3A4/5 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4/5 inhibitor significantly increased the plasma exposure of axitinib in healthy volunteers.
    Azelastine; Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate.
    Bedaquiline: (Major) Concurrent use of bedaquiline and cobicistat should be avoided due to the potential risk of adverse reactions to bedaquiline because of increased systemic exposure. Bedaquiline is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased bedaquiline exposure by 22%.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Contraindicated) Coadministration of ergotamine with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues. (Contraindicated) Coadministration of phenobarbital with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Benzhydrocodone; Acetaminophen: (Moderate) Concurrent use of benzhydrocodone with cobicistat may increase the risk of increased opioid-related adverse reactions, such as fatal respiratory depression. Consider a dose reduction of benzhydrocodone until stable drug effects are achieved. Monitor patients for respiratory depression and sedation at frequent intervals. Discontinuation of cobicistat in a patient taking benzhydrocodone may decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to opioid agonists. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Benzhydrocodone is a prodrug for hydrocodone. Hydrocodone is a substrate for CYP3A4 and CYP2D6. Cobicistat is a strong inhibitor of CYP3A4 and a weak inhibitor of CYP2D6.
    Bepridil: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of bepridil with cobicistat. Bepridil is a substrate for CYP3A4; cobicistat is an inhibitor of this enzyme. Concurrent use may result in elevated bepridil plasma concentration.
    Berotralstat: (Major) Reduce the berotralstat dose to 110 mg PO once daily in patients chronically taking cobicistat. Concurrent use may increase berotralstat exposure and the risk of adverse effects. Additionally, monitor for cobicistat-related adverse effects as concurrent use may also increase cobicistat exposure. Berotralstat is a P-gp and BCRP substrate and moderate CYP3A4 inhibitor; cobicistat is a CYP3A4 substrate and P-gp and BCRP inhibitor. Coadministration with another P-gp and BCRP inhibitor increased berotralstat exposure by 69%.
    Betamethasone: (Moderate) Monitor for corticosteroid-related adverse effects if coadministration is necessary. Consider using an alternative treatment to betametasone, such as a corticosteroid less affected by CYP3A4 (i.e., beclomethasone or prednisolone), particularly if long term use is indicated. Cobicistat is a strong CYP3A4 inhibitor and betamethasone is a CYP3A4 substrate. Another strong CYP3A4 inhibitor has been reported to decrease the metabolism of certain corticosteroids by up to 60%, leading to increased risk of corticosteroid side effects.
    Betrixaban: (Major) Avoid betrixaban use in patients with severe renal impairment receiving cobicistat. Reduce betrixaban dosage to 80 mg PO once followed by 40 mg PO once daily in all other patients receiving cobicistat. Bleeding risk may be increased; monitor patients closely for signs and symptoms of bleeding. Betrixaban is a substrate of P-gp; cobicistat inhibits P-gp.
    Bexarotene: (Major) Coadministration of cobicistat with bexarotene is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Bexarotene is a CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
    Boceprevir: (Major) Avoid concurrent use of cobicistat with boceprevir, as drug interaction data are not available. Clinically significant drug interactions may occur during coadministration. Boceprevir is a CYP3A4 inhibitor/substrate and P-glycoprotein (P-gp) substrate. Cobicistat is an inhibitor of CYP3A4 and P-gp, and a substrate of CYP3A4.
    Bortezomib: (Moderate) Monitor for signs of bortezomib toxicity and consider a bortezomib dose reduction if coadministration of cobicistat is necessary. Bortezomib exposure may be increased. Bortezomib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased bortezomib exposure by 35%.
    Bosentan: (Major) The plasma concentrations of bosentan may increase when administered with regimens containing cobicistat and atazanavir or darunavir. In addition, coadministration may result in decreased concentrations of cobicistat, atazanavir, and darunavir. In patients receiving the antiretrovirals for at least 10 days, start bosentan at 62.5 mg daily or every other day (depending on tolerability). When the antiretrovirals are initiated in a patients currently receiving bosentan, discontinue bosentan at least 36 hours prior to starting the antiretroviral regimen. After at least 10 days, restart bosentan at 62.5 mg daily or every other day based on tolerability. If switching from a ritonavir boosted antiretroviral regimen to a cobicistat boosted regimen, maintain current bosentan dose.
    Bosutinib: (Major) Avoid concomitant use of bosutinib and cobicistat; bosutinib plasma exposure may be significantly increased resulting in an increased risk of bosutinib adverse events (e.g., myelosuppression, GI toxicity). Bosutinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The Cmax and AUC values of bosutinib were increased 5.2-fold and 8.6-fold, respectively, when a single oral dose of bosutinib 100 mg PO was administered after 5 days of a strong CYP3A4 inhibitor.
    Brentuximab vedotin: (Moderate) Closely monitor for an increase in brentuximab-related adverse reactions, including peripheral neuropathy or gastrointestinal side effects, if coadministration with cobicistat is necessary. Monomethyl auristatin E (MMAE), one of the 3 components released from brentuximab vedotin, is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased MMAE exposure by approximately 34%.
    Brexpiprazole: (Major) Because brexpiprazole is primarily metabolized by CYP3A4 and CYP2D6, the manufacturer recommends that the brexpiprazole dose be reduced to one-quarter (25%) of the usual dose in patients receiving a moderate to strong inhibitor of CYP3A4 in combination with a moderate to strong inhibitor of CYP2D6. Cobicistat is a moderate to strong inhibitor of both CYP3A4 and CYP2D6. If these agents are used in combination, the patient should be carefully monitored for brexpiprazole-related adverse reactions. If cobicistat is discontinued, adjust the brexpiprazole dosage to its original level.
    Brigatinib: (Major) Avoid coadministration of brigatinib with cobicistat if possible due to increased plasma exposure of brigatinib; an increase in brigatinib-related adverse reactions may occur. If concomitant use is unavoidable, reduce the dose of brigatinib by approximately 50% without breaking tablets (i.e., from 180 mg to 90 mg; from 90 mg to 60 mg); after discontinuation of cobicistat, resume the brigatinib dose that was tolerated prior to initiation of cobicistat. Brigatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of brigatinib by 101% and 21%, respectively.
    Brimonidine; Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
    Bromocriptine: (Major) When bromocriptine is used for diabetes, avoid coadministration with cobicistat ensuring adequate washout before initiating bromocriptine. Use this combination with caution in patients receiving bromocriptine for other indications. Concurrent use may significantly increase bromocriptine concentrations. Bromocriptine is extensively metabolized in the liver via CYP3A4; cobicistat is a strong inhibitor of CYP3A4.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Brompheniramine; Guaifenesin; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Budesonide: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Budesonide; Formoterol: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Budesonide; Glycopyrrolate; Formoterol: (Moderate) Avoid coadministration of oral budesonide and cobistat due to the potential for increased budesonide exposure. Use caution with inhaled forms of budesonide as systemic exposure to the corticosteroid may also increase. Elevated budesonide serum concentrations may result in Cushing's syndrome and adrenal suppression. Budesonide is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and P-gp. In the presence of another strong CYP3A4 inhibitor, the systemic exposure to oral budesonide was increased by 8-fold. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Bupivacaine Liposomal: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
    Bupivacaine: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
    Bupivacaine; Lidocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
    Bupivacaine; Meloxicam: (Minor) Plasma concentrations of bupivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as cardiotoxic effects, hypotension, or CNS toxicity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while bupivacaine is a CYP3A4 substrate.
    Buprenorphine: (Moderate) Concomitant use of buprenorphine and cobicistat can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when cobicistat is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping cobicistat, the buprenorphine concentration will decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If cobicistat is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A4. cobicistat is a strong CYP3A4 inhibitor.
    Buprenorphine; Naloxone: (Moderate) Concomitant use of buprenorphine and cobicistat can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when cobicistat is added after a stable buprenorphine dose is achieved. If concurrent use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patient for respiratory depression and sedation at frequent intervals. When stopping cobicistat, the buprenorphine concentration will decrease, potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependency. If cobicistat is discontinued, consider increasing buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. Buprenorphine is a substrate of CYP3A4. cobicistat is a strong CYP3A4 inhibitor. (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
    Bupropion: (Moderate) Caution is warranted when cobicistat is administered with bupropion as there is a potential for elevated cobicistat concentrations. Bupropion is a CYP2D6 inhibitor in vitro, while cobicistat is a substrate of CYP2D6.
    Bupropion; Naltrexone: (Moderate) Caution is warranted when cobicistat is administered with bupropion as there is a potential for elevated cobicistat concentrations. Bupropion is a CYP2D6 inhibitor in vitro, while cobicistat is a substrate of CYP2D6.
    Buspirone: (Moderate) A low dose of buspirone used cautiously is recommended when coadministered with cobicistat. If a patient has been titrated to a stable dosage of buspirone, a dose adjustment of buspirone may be necessary to avoid adverse events attributable to buspirone. Administering cobicistat with buspirone may increase buspirone concentration and risk for adverse events. Buspirone is a sensitive substrate of CYP3A4. Cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the buspirone AUC by 19-fold with an increased incidence of buspirone-related adverse effects.
    Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Cabazitaxel: (Major) Avoid coadministration of cabazitaxel with cobicistat if possible due to increased cabazitaxel exposure. If concomitant use is unavoidable, consider reducing the dose of cabazitaxel by 25%. Cabazitaxel is primarily metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration with another strong CYP3A4 inhibitor increased cabazitaxel exposure by 25%.
    Cabotegravir; Rilpivirine: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
    Cabozantinib: (Major) Avoid concomitant use of cabozantinib and cobicistat due to the risk of increased cabozantinib exposure which may increase the incidence and severity of adverse reactions. If concomitant use is unavoidable, reduce the dose of cabozantinib. For patients taking cabozantinib tablets, reduce the dose of cabozantinib by 20 mg; for patients taking cabozantinib capsules, reduce the dose of cabozantinib by 40 mg. Resume the cabozantinib dose that was used prior to initiating treatment with cobicistat 2 to 3 days after discontinuation of cobicistat. Cabozantinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased cabozantinib exposure by 38%.
    Canagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Capmatinib: (Moderate) Monitor for an increase in capmatinib-related adverse reactions if coadministration with cobicistat is necessary. Capmatinib is a CYP3A substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased capmatinib exposure by 42%.
    Carbamazepine: (Contraindicated) Coadministration of carbamazepine with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. In addition, inhibition of CYP3A4 by cobicistat may result in elevated carbamazepine concentrations. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Carbetapentane; Chlorpheniramine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Cariprazine: (Major) The dose of cariprazine should be reduced in patients also receiving cobicistat. When cobicistat is initiated in a patient who is on a stable dose of cariprazine, reduce the cariprazine dosage by half. For adult patients taking cariprazine 4.5 mg daily, the dosage should be reduced to 1.5 mg or 3 mg daily. For patients taking cariprazine 1.5 mg daily, the dosing frequency should be adjusted to every other day. When initiating cariprazine in a patient who is stable on cobicistat, the patient should be administered 1.5 mg of cariprazine on Day 1 and on Day 3 with no dose administered on Day 2. From Day 4 onward, the dose should be administered at 1.5 mg daily, and then increased to a maximum dose of 3 mg daily. If cobicistat is withdrawn, the cariprazine dosage may need to be increased. Cariprazine is metabolized by CYP3A4 to its major active metabolite. Cobicistat is a strong CYP3A4 inhibitor. Concurrent use with another strong CYP3A4 inhibitor increased the exposure of cariprazine by about 4-fold; increased the AUC of DDCAR metabolite by about 1.5-fold; and decreased DCAR metabolite AUC by about one-third.
    Carvedilol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as carvedilol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advise.
    Cenobamate: (Moderate) Coadministration of cobicistat with cenobamate may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and cenobamate is a moderate CYP3A4 inducer.
    Ceritinib: (Major) Avoid concomitant use of ceritinib with cobicistat due to increased ceritinib exposure which may increase the incidence and severity of adverse reactions; cobicistat exposure may also increase. If concomitant use is necessary, decrease the dose of ceritinib by approximately one-third, rounded to the nearest multiple of 150 mg and monitor for ceritinib-related adverse reactions. After cobicistat is discontinued, resume the dose of ceritinib taken prior to initiating cobicistat. Both drugs are CYP3A substrates and strong CYP3A4 inhibitors. Coadministration with a strong CYP3A inhibitor increased ceritinib exposure by 2.9-fold.
    Cerivastatin: (Moderate) The plasma concentrations of cerivastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or hepatotoxicity, is recommended during coadministration. Cobicistat is a CYP3A4 and organic anion transport protein (OATP) inhibitor, while cerivastatin is a CYP3A4 and OATP substrate.
    Chloramphenicol: (Moderate) Caution is warranted when cobicistat is administered with chloramphenicol as there is a potential for elevated cobicistat concentrations. Chloramphenicol is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4.
    Chlordiazepoxide: (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
    Chlordiazepoxide; Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations. (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
    Chlordiazepoxide; Clidinium: (Moderate) The plasma concentrations of chlordiazepoxide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while chlordiazepoxide is a CYP3A4 substrate.
    Chlorpheniramine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Chlorpheniramine; Codeine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Chlorpheniramine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Chlorpheniramine; Hydrocodone: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Chlorpheniramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Chlorpheniramine; Pseudoephedrine: (Moderate) Caution is warranted when cobicistat is administered with chlorpheniramine as there is a potential for elevated chlorpheniramine and cobicistat concentrations. Chlorpheniramine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Chlorpromazine: (Major) Caution is warranted when cobicistat is administered with chlorpromazine as there is a potential for elevated chlorpromazine and cobicistat concentrations. Chlorpromazine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Ciclesonide: (Moderate) Coadministration of ciclesonide with cobicistat may cause elevated ciclesonide serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Ciclesonide is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Cilostazol: (Major) Reduce the dose of cilostazol to 50 mg twice daily when coadministered with cobicistat. Monitor for an increase in cilostazol-related adverse reactions. Cobicistat is a strong CYP3A4 inhibitor and cilostazol is a CYP3A4 substrate. Coadministration of another strong CYP3A4 inhibitor increased the cilostazol AUC by 117%.
    Cinacalcet: (Moderate) Dose adjustment of cinacalcet may be required if a patient initiates or discontinues therapy with cobicistat; closely monitor iPTH and serum calcium concentrations. Cinacalcet is partially metabolized by CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC and Cmax of cinacalcet by 127% and 116%, respectively.
    Cisapride: (Contraindicated) Coadministration of cisapride with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A4, and plasma concentrations of drugs extensively metabolized by this enzyme, such as cisapride, are expected to increase with concurrent use. Elevated plasma concentrations of cisapride have been associated with QT prolongation and serious cardiovascular adverse events including death due to torsade de pointes.
    Citalopram: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Clarithromycin: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir.
    Clindamycin: (Moderate) Monitor for an increase in clindamycin-related adverse reactions with coadministration of cobicistat as concurrent use may increase clindamycin exposure. Clindamycin is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4.
    Clobazam: (Major) Coadministration of cobicistat with clobazam is not recommended. There is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Clobazam is a weak inducer of CYP3A4. Cobicistat is a substrate of CYP3A4.
    Clomipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Clonazepam: (Moderate) Monitor for increased sedation and respiratory depression if clonazepam is coadministered with cobicistat; adjust the dose of clonazepam if necessary. The systemic exposure of clonazepam may be increased resulting in increase in treatment-related adverse reactions. Cobicistat is a strong CYP3A4 inhibitor and clonazepam is a CYP3A4 substrate.
    Clopidogrel: (Major) Avoid coadministration of clopidogrel with cobicistat due to the potential for decreased clopidogrel efficacy. Prasugrel may be preferred to clopidogrel if coadministration with cobicistat is necessary. Although clopidogrel is primarily converted to its active metabolite via CYP2C19, it has been suggested that inhibition of CYP3A4 also reduces its conversion to the active metabolite, thereby reducing its antiplatelet effect. Cobicistat is a strong CYP3A4 inhibitor.
    Clorazepate: (Moderate) Use caution if coadministration of cobicistat with clorazepate is necessary, as the systemic exposure of the active metabolite of clorazepate may be increased resulting in an increase in treatment-related adverse reactions; adjust the dose of clorazepate if necessary. Cobicistat is a strong CYP3A4 inhibitor. Clorazepate is a pro-drug converted to N-desmethyldiazepam in the GI tract; N-desmethyldiazepam is metabolized by 2C19 and 3A4.
    Clozapine: (Moderate) Caution is advisable during concurrent use of cobicistat and clozapine. Cobicistat is an inhibitor of CYP2D6 and CYP3A4, two of the isoenzymes responsible for the metabolism of clozapine. Elevated plasma concentrations of clozapine occurring through CYP inhibition may potentially increase the risk of life-threatening arrhythmias, sedation, anticholinergic effects, seizures, orthostasis, or other adverse effects. According to the manufacturer, patients receiving clozapine in combination with a CYP3A4 or CYP2D6 inhibitor should be monitored for adverse reactions. Consideration should be given to reducing the clozapine dose if necessary. If the inhibitor is discontinued after dose adjustments are made, monitor for lack of clozapine effectiveness and consider increasing the clozapine dose if necessary.
    Cobimetinib: (Major) Avoid the concurrent use of cobimetinib with chronic cobicistat due to the risk of cobimetinib toxicity. If concurrent short-term (14 days or less) use of cobicistat is unavoidable, reduce the dose of cobimetinib to 20 mg once daily for patients normally taking 60 mg daily; after discontinuation of cobicistat, resume cobimetinib at the previous dose. Use an alternative to cobicistat in patients who are already taking a reduced dose of cobimetinib (40 or 20 mg daily). Cobimetinib is a P-glycoprotein (P-gp) substrate as well as a CYP3A substrate in vitro; cobicistat is a moderate inhibitor of both P-gp and CYP3A. In healthy subjects (n = 15), coadministration of a single 10 mg dose of cobimetinib with itraconazole (200 mg once daily for 14 days), a strong CYP3A4 inhibitor, increased the mean cobimetinib AUC by 6.7-fold (90% CI, 5.6 to 8) and the mean Cmax by 3.2-fold (90% CI, 2.7 to 3.7).
    Cocaine: (Moderate) Caution is warranted when cobicistat is administered with cocaine as there is a potential for elevated concentrations of both drugs. Clinical monitoring for adverse effects is recommended during coadministration. Both drugs are substrates and inhibitors of CYP3A4. Cocaine is also an inhibitor of CYP2D6; cobicistat is a CYP2D6 substrates/inhibitors.
    Codeine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Codeine; Guaifenesin: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Codeine; Phenylephrine; Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Codeine; Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Concomitant use of codeine with cobicistat may increase codeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased morphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. It is recommended to avoid this combination when codeine is being used for cough. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of codeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease codeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to codeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Cobicistat is a strong inhibitor of CYP3A4.
    Colchicine: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and cobicistat in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Cobicistat can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken a P-gp/strong CYP3A4 inhibitor like cobicistat in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day.
    Conivaptan: (Contraindicated) Coadministration of conivaptan and cobicistat is contraindicated due to the potential for increased conivaptan exposure. Concomitant use may also increase cobicistat exposure and risk for cobicistat-related adverse effects. Conivaptan is a CYP3A substrate and moderate CYP3A inhibitor; cobicistat is a CYP3A substrate and strong CYP3A inhibitor. In a drug interaction study, coadministration of a strong CYP3A inhibitor increased the exposure of oral conivaptan by 11-fold.
    Conjugated Estrogens; Medroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with medroxyprogesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Copanlisib: (Major) Avoid the concomitant use of copanlisib and cobicistat if possible; increased copanlisib exposure may occur. If coadministration cannot be avoided, reduce the copanlisib dose to 45 mg and monitor patients for copanlisib-related adverse events (e.g., hypertension, infection, and skin rash). Copanlisib is a CYP3A substrate; cobicistat is a strong CYP3A inhibitor. The AUC of copanlisib increased by 53% when a single IV dose of copanlisib 60 mg was administered following 10 days of another strong CYP3A4 inhibitor in a drug interaction study in patients with cancer.
    Crizotinib: (Major) Avoid concomitant use of cobicistat and crizotinib due to increased plasma concentrations of crizotinib, which may increase the incidence and severity of adverse reactions; increased cobicistat exposure may also occur. If concomitant use is necessary for patients with non-small cell lung cancer, reduce the dose of crizotinib to 250 mg PO once daily. If concomitant use is necessary for patients with anaplastic large cell lymphoma, reduce the dose of crizotinib to 250 mg PO twice daily for BSA of 1.7 m2 or more; 200 mg PO twice daily for BSA of 1.17 to 1.69 m2; and 250 mg PO once daily for BSA of 0.81 to 1.16 m2; do not use this combination in patients with a BSA of 0.6 to 0.8 m2. Resume the original crizotinib dose after discontinuation of cobicistat. Crizotinib is a CYP3A substrate and moderate inhibitor. Cobicistat is a CYP3A4 substrate and strong inhibitor. Coadministration with one strong CYP3A inhibitor increased the AUC of single-dose crizotinib by 216%. Concomitant use with another strong CYP3A4 inhibitor increased the steady-state AUC of crizotinib by 57% compared to crizotinib alone.
    Cyclosporine: (Moderate) Cyclosporine therapeutic drug monitoring is recommended when administered concurrently with cobicistat. Use of these medications together may result in elevated cyclosporine serum concentrations, causing an increased risk for cyclosporine-related adverse events. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of cyclosporine.
    Dabigatran: (Moderate) Avoid the coadministration of dabigatran and cobicistat in patients with severe renal impairment (CrCl less than 30 mL/minute). When dabigatran is administered for treatment or reduction in risk of recurrence of deep venous thrombosis (DVT) or pulmonary embolism (PE) or prophylaxis of DVT or PE following hip replacement surgery, avoid coadministration with P-gp inhibitors like cobicistat in patients with CrCl less than 50 mL/minute. Coadministration may result in increased dabigatran serum concentrations, increasing the risk of dabigatran adverse effects. Dabigatran is a substrate of p-glycoprotein (P-gp) and cobicistat is a P-gp inhibitor. P-gp inhibition and renal impairment are the major independent factors that result in increased exposure to dabigatran.
    Dabrafenib: (Major) Avoid coadministration of dabrafenib and cobicistat due to the potential for decreased cobicistat concentrations and increased dabrafenib exposure. If another agent cannot be substituted and coadministration of these agents is unavoidable, monitor patients closely for reduced antiretroviral efficacy and dabrafenib adverse reactions including skin toxicity, ocular toxicity, and cardiotoxicity. Both drugs are CYP3A4 substrates. Darafenib is a moderate CYP3A4 inducer, while cobicistat is a strong CYP3A4 inhibitor. In a drug interaction study, coadministration of a strong CYP3A4 inhibitor increased the dabrafenib AUC by 71%, hydroxy-dabrafenib AUC by 82%, and desmethyl-dabrafenib AUC by 68%
    Daclatasvir: (Major) The dose of daclatasvir, a CYP3A4 substrate, must be reduced to 30 mg PO once daily when administered in combination with strong CYP3A4 inhibitors, such as cobicistat. Taking these drugs together may increase daclatasvir serum concentrations, and potentially increase the risk for adverse effects.
    Danazol: (Moderate) Caution is warranted when cobicistat is administered with danazol as there is a potential for elevated cobicistat concentrations. Danazol is a CYP3A4 inhibitor and cobicistat is a substrate of CYP3A4.
    Dapagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Dapagliflozin; Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively.
    Dapsone: (Minor) Plasma concentrations of dapsone may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hemolytic anemia, methemoglobinemia, or peripheral neuropathy, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while dapsone is a CYP3A4 substrate.
    Darifenacin: (Major) The daily dose of darifenacin should not exceed 7.5 mg PO when administered with cobicistat due to increased darifenacin exposure. Darifenacin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor.
    Darolutamide: (Moderate) Monitor patients more frequently for darolutamide-related adverse reactions if coadministration with cobicistat is necessary due to the risk of increased darolutamide exposure; decrease the dose of darolutamide for grade 3 or 4 adverse reactions or for otherwise intolerable adverse reactions. Cobicistat is a P-glycoprotein (P-gp) inhibitor and a strong CYP3A4 inhibitor; darolutamide is a CYP3A4 substrate. Concomitant use with another combined P-gp inhibitor and strong CYP3A4 inhibitor increased the mean AUC and Cmax of darolutamide by 1.7-fold and 1.4-fold, respectively.
    Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. (Moderate) Monitor for an increase in paritaprevir-related adverse reactions if coadministration with cobicistat is necessary. Paritaprevir is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased paritaprevir exposure by 2.2-fold to 2.9-fold.
    Dasatinib: (Major) Avoid coadministration of dasatinib and cobicistat due to the potential for increased dasatinib exposure and subsequent toxicity. An alternative to cobicistat with no or minimal enzyme inhibition potential is recommended if possible. If coadministration cannot be avoided, consider a dasatinib dose reduction to 40 mg PO daily if original dose was 140 mg daily, 20 mg PO daily if original dose was 100 mg daily, or 20 mg PO daily if original dose was 70 mg daily. Concomitant use of cobicistat is not recommended in patients receiving dasatinib 60 mg or 40 mg daily. If dasatinib is not tolerated after dose reduction, consider alternative therapies. If cobicistat is stopped, allow a washout of approximately 1 week before increasing the dasatinib dose. Dasatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the mean Cmax and AUC of dasatinib by 4-fold and 5-fold, respectively.
    Deflazacort: (Major) Decrease deflazacort dose to one third of the recommended dosage when coadministered with cobicistat. Concurrent use may significantly increase concentrations of 21-desDFZ , the active metabolite of deflazacort, resulting in an increased risk of toxicity. Deflazacort is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Administration of deflazacort with another strong CYP3A4 inhibitor, increased total exposure to 21-desDFZ by about 3-fold.
    Delavirdine: (Moderate) The plasma concentrations of delavirdine and cobicistat may be elevated when administered concurrently. Clinical monitoring for adverse effects is recommended during coadministration. Delavirdine is a CYP2D6 and CYP3A4 substrate/inhibitor. Cobicistat is a substrate/inhibitor of both CYP2D6 and CYP3A4.
    Desipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Desogestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with desogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Desvenlafaxine: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Dexamethasone: (Major) Avoid concurrent use of dexamethasone with cobicistat containing regimens. Coadministration may result in a reduction of antiretroviral efficacy and the potential development of viral resistance. In addition, serum concentrations of dexamethasone may be increased, potentially resulting in Cushing's syndrome and adrenal suppression. Dexamethasone is a CYP3A4 substrate and inducer; cobicistat is a substrate of this enzyme as well as a strong CYP3A inhibitor. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dexlansoprazole: (Minor) The plasma concentrations of dexlansoprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dexlansoprazole is a CYP3A4 substrate.
    Dextromethorphan: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Guaifenesin: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Dextromethorphan; Quinidine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of quinidine with cobicistat. Quinidine is a substrate for CYP3A4 and P-glycoprotein (P-gp) and an inhibitor of CYP2D6 and P-gp; cobicistat is a substrate and inhibitor of both these enzymes and an inhibitor of P-gp. Concurrent use may result in elevated plasma concentration of both drugs. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Diazepam: (Moderate) The plasma concentrations of diazepam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; diazepam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of diazepam. These drugs used in combination may result in elevated diazepam plasma concentrations, causing an increased risk for diazepam-related adverse events.
    Diclofenac: (Moderate) Caution is warranted when cobicistat is administered with diclofenac as there is a potential for increased diclofenac concentrations. Diclofenac is a substrate of CYP3A4 and CYP2C9. Cobicistat is an inhibitor of CYP3A4.
    Diclofenac; Misoprostol: (Moderate) Caution is warranted when cobicistat is administered with diclofenac as there is a potential for increased diclofenac concentrations. Diclofenac is a substrate of CYP3A4 and CYP2C9. Cobicistat is an inhibitor of CYP3A4.
    Dienogest; Estradiol valerate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with dienogest. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Digoxin: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of digoxin with cobicistat. Digoxin is a substrate for P-gp; cobicistat is an inhibitor of this drug transporter. Concurrent use may result in elevated digoxin plasma concentration.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Moderate) Concomitant use of dihydrocodeine with cobicistat may increase dihydrocodeine plasma concentrations, resulting in greater metabolism by CYP2D6, increased dihydromorphine concentrations, and prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of dihydrocodeine until stable drug effects are achieved. Discontinuation of cobicistat could decrease dihydrocodeine plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to dihydrocodeine. If cobicistat is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
    Dihydroergotamine: (Contraindicated) Coadministration of dihydroergotamine with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
    Diltiazem: (Moderate) Monitor blood pressure and heart rate if coadministration of diltiazem with cobicistat is necessary. Diltiazem is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Diphenhydramine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6. (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Diphenhydramine; Ibuprofen: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Diphenhydramine; Naproxen: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Diphenhydramine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with diphenhydramine as there is a potential for elevated diphenhydramine and cobicistat concentrations. Diphenhydramine is a substrate/inhibitor of CYP2D6 and a substrate of CYP2C9. Cobicistat is an substrate/inhibitor of CYP2D6.
    Disopyramide: (Major) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of disopyramide with cobicistat. Disopyramide is a substrate for CYP3A4; cobicistat is a strong inhibitor of this enzyme. Concurrent use may result in elevated disopyramide plasma concentration. Cases of life-threatening interactions have been reported for disopyramide when given with another strong CYP3A4 inhibitor.
    Disulfiram: (Moderate) The plasma concentrations of disulfiram may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while disulfiram is a CYP3A4 substrate.
    Docetaxel: (Major) Avoid coadministration of docetaxel with cobicistat if possible due to increased plasma concentrations of docetaxel. If concomitant use is unavoidable, closely monitor for docetaxel-related adverse reactions and consider a 50% dose reduction of docetaxel. Docetaxel is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased docetaxel exposure by 2.2-fold.
    Dolasetron: (Moderate) The plasma concentrations of hydrodolasetron (primary dolasetron metabolite) may be elevated when dolasetron is administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as headache or cardiovascular effects, is recommended during coadministration. Cobicistat is a CYP3A4 and CYP2D6 inhibitor, while hydrodolasetron is a CYP3A4 and CYP2D6 substrate.
    Dolutegravir: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
    Dolutegravir; Lamivudine: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp.
    Dolutegravir; Rilpivirine: (Moderate) Caution is warranted when cobicistat is administered with dolutegravir as there is a potential for elevated dolutegravir concentrations. Dolutegravir is a substrate of CYP3A4 and P-glycoprotein (P-gp). Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of P-gp. (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
    Donepezil: (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate.
    Donepezil; Memantine: (Moderate) The plasma concentrations of donepezil may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or cholinergic effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor, while donepezil is a CYP3A4 and CYP2D6 substrate.
    Doravirine: (Minor) Coadministration of doravirine and cobicistat may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; cobicistat is a strong inhibitor. In drug interaction studies, concurrent use of strong CYP3A4 inhibitors increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant.
    Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Minor) Coadministration of doravirine and cobicistat may result in increased doravirine plasma concentrations. Doravirine is a CYP3A4 substrate; cobicistat is a strong inhibitor. In drug interaction studies, concurrent use of strong CYP3A4 inhibitors increased doravirine exposure by more than 3-fold; however, this increase was not considered clinically significant.
    Dorzolamide; Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
    Doxazosin: (Moderate) Monitor blood pressure and for signs of hypotension during coadministration. The plasma concentrations of doxazosin may be elevated when administered concurrently with cobicistat. Cobicistat is a strong CYP3A4 inhibitor; doxazosin is a CYP3A4 substrate. Coadministration of doxazosin with a moderate CYP3A4 inhibitor resulted in a 10% increase in mean AUC and an insignificant increase in mean Cmax and mean half-life of doxazosin. Although not studied in combination with doxazosin, strong CYP3A4 inhibitors may have a larger impact on doxazosin concentrations and therefore should be used with caution.
    Doxepin: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Doxorubicin Liposomal: (Major) Avoid coadministration of cobicistat and doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp); doxorubicin is a major CYP2D6, CYP3A4, and P-gp substrate. Clinically significant interactions have been reported when doxorubicin was coadministered with inhibitors of CYP2D6, CYP3A4, and/or P-gp, resulting in increased concentration and clinical effect of doxorubicin.
    Doxorubicin: (Major) Avoid coadministration of cobicistat and doxorubicin due to increased systemic exposure of doxorubicin resulting in increased treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp); doxorubicin is a major CYP2D6, CYP3A4, and P-gp substrate. Clinically significant interactions have been reported when doxorubicin was coadministered with inhibitors of CYP2D6, CYP3A4, and/or P-gp, resulting in increased concentration and clinical effect of doxorubicin.
    Dronabinol: (Moderate) Use caution if coadministration of dronabinol with cobicistat is necessary, and closely monitor for an increase in dronabinol-related adverse reactions (e.g., cognitive impairment, psychosis, seizures, and hemodynamic instability, as well as feeling high, dizziness, confusion, somnolence). Concomitant use may result in elevated plasma concentrations of dronabinol. Cobicistat is a strong inhibitor of CYP3A4; dronabinol is a CYP2C9 and 3A4 substrate.
    Dronedarone: (Contraindicated) Coadministration of cobicistat with dronedarone is contraindicated due to the potential for elevated dronedarone concentrations. Dronedarone is a CYP3A4 inhibitor/substrate and a CYP2D6 inhibitor. Cobicistat is an inhibitor/substrate of both CYP3A4 and CYP2D6.
    Drospirenone: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms.
    Drospirenone; Estetrol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms.
    Drospirenone; Estradiol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms.
    Drospirenone; Ethinyl Estradiol: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Drospirenone may be administered concurrently with cobicistat; however, close clinical monitoring for adverse events such as hyperkalemia is recommended. Taking drospirenone with cobicistat may increase drospirenone serum concentrations. Instruct women to report adverse events to their prescribers. Further, because hormonal contraceptives do not protect against the transmission of HIV/AIDS and other sexually transmitted diseases, women who receive these drugs together should use an additional barrier method of contraception such as condoms. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Duloxetine: (Moderate) Caution is warranted when cobicistat is administered with duloxetine as there is a potential for elevated duloxetine and cobicistat concentrations. Duloxetine is a CYP2D6 substrate/inhibitor. Cobicistat is a substrate/inhibitor of CYP2D6.
    Dutasteride: (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
    Dutasteride; Tamsulosin: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
    Duvelisib: (Major) Reduce duvelisib dose to 15 mg PO twice daily and monitor for increased toxicity when coadministered with cobicistat. Coadministration may increase the exposure of duvelisib. Duvelisib is a CYP3A substrate; cobicistat is a strong CYP3A inhibitor. The increase in exposure to duvelisib is estimated to be approximately 2-fold when used concomitantly with strong CYP3A inhibitors such as cobicistat.
    Edoxaban: (Moderate) Coadministration of edoxaban and cobicistat may result in increased concentrations of edoxaban. Edoxaban is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor. Increased concentrations of edoxaban may occur during concomitant use of cobicistat; monitor for increased adverse effects of edoxaban. Dosage reduction may be considered for patients being treated for deep venous thrombosis (DVT) or pulmonary embolism.
    Efavirenz: (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and daruanavir and atazanavir are CYP3A4 substrates.
    Efavirenz; Emtricitabine; Tenofovir: (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and daruanavir and atazanavir are CYP3A4 substrates.
    Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) Due to the potential for decreased antiretroviral efficacy, use of efavirenz with cobicistat and darunavir should be avoided. In addition, efavirenz is not recommended for use in combination with cobicistat and atazanavir in antiretroviral-experienced patients; however, this combination may be used in treatment-naive patients if the following dose recommendations are followed: cobicistat 150 mg PO and atazanavir 400 mg PO once daily with food, plus efavirenz 600 mg once daily on an empty stomach. When these drugs are given together, the concentrations of cobicistat, darunavir, and atazanavir are decreased. Efavirenz is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, and daruanavir and atazanavir are CYP3A4 substrates.
    Elagolix: (Contraindicated) Concomitant use of elagolix and strong organic anion transporting polypeptide (OATP) 1B1 inhibitors such as cobicistat is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of CYP3A, P-gp, and OATP1B1. Cobicistat is a combined inhibitor; it is a potent inhibitor of CYP3A and inhibits OATP1B1 and P-gp. Another OATP1B1 potent inhibitor increased elagolix AUC in the range of 2- to 5.58-fold. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density.
    Elagolix; Estradiol; Norethindrone acetate: (Contraindicated) Concomitant use of elagolix and strong organic anion transporting polypeptide (OATP) 1B1 inhibitors such as cobicistat is contraindicated. Use of elagolix with drugs that inhibit OATP1B1 may increase elagolix plasma concentrations. Elagolix is a substrate of CYP3A, P-gp, and OATP1B1. Cobicistat is a combined inhibitor; it is a potent inhibitor of CYP3A and inhibits OATP1B1 and P-gp. Another OATP1B1 potent inhibitor increased elagolix AUC in the range of 2- to 5.58-fold. Increased elagolix concentrations increase the risk for dose-related side effects, including loss of bone mineral density. (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Elbasvir; Grazoprevir: (Major) Concurrent administration of elbasvir with cobicistat is not recommended. Use of these drugs together is expected to significantly increase the plasma concentrations of elbasvir and may result in adverse effects (i.e., elevated ALT concentrations). Cobicistat is a strong inhibitor of the hepatic enzyme CYP3A, while elbasvir is metabolized by CYP3A. (Major) Concurrent administration of grazoprevir with cobicistat should be avoided if possible. Use of these drugs together is expected to significantly increase the plasma concentrations of grazoprevir and may result in adverse effects (i.e., elevated ALT concentrations). Cobicistat is an inhibitor of the hepatic enzyme CYP3A, while grazoprevir is metabolized by CYP3A.
    Eletriptan: (Contraindicated) Eletriptan is contraindicated with recent use (i.e., within 72 hours) of cobicistat due to the potential for increased eletriptan exposure. Eletriptan is a sensitive substrate of CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the Cmax and AUC of eletriptan by 3-fold and 6-fold, respectively.
    Elexacaftor; tezacaftor; ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Major) Reduce the dosing frequency of elexacaftor; tezacaftor; ivacaftor when coadministered with cobicistat; coadministration may increase elexacaftor; tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 2 elexacaftor/tezacaftor/ivacaftor combination tablets twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Elexacaftor, tezacaftor, and ivacaftor are CYP3A4 substrates (ivacaftor is a sensitive substrate); cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased elexacaftor exposure by 2.8- fold, tezacaftor exposure by 4.5-fold, and ivacaftor exposure by 15.6-fold. (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with cobicistat; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor/ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); cobicistat is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively.
    Eliglustat: (Major) Coadministration of eliglustat and cobicistat is contraindicated in intermediate or poor CYP2D6 metabolizers (IMs or PMs). In extensive CYP2D6 metabolizers (EMs), coadministration of these agents requires dosage reduction of eliglustat to 84 mg PO once daily. The coadministration of eliglustat with cobicistat and a moderate or strong CYP2D6 inhibitor is contraindicated in all patients. Eliglustat is a CYP3A and CYP2D6 substrate. Coadministration of eliglustat with CYP3A inhibitors, such as cobicistat, increases eliglustat exposure and the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias); this risk is the highest in CYP2D6 IMs and PMs because a larger portion of the eliglustat dose is metabolized via CYP3A. The product labeling for cobicistat states that coadministration of other drugs for which altered plasma concentrations are associated with serious and/or life-threatening effects is contraindicated; however, the interaction between ketoconazole (another potent CYP3A inhibitor) and eliglustat was studied during clinical trials. The resultant data supports eliglustat dosage reduction in EMs instead of contraindication.
    Eluxadoline: (Major) When administered concurrently with cobicistat, the dose of eluxadoline must be reduced to 75 mg PO twice daily, and the patient should be closely monitored for eluxadoline-related adverse effects (i.e., decreased mental and physical acuity). Eluxadoline is a substrate of the organic anion-transporting peptide (OATP1B1); cobicistat is an OATP1B1/1B3 inhibitor. Advise patients against driving or operating machinery until the combine effects of these drugs on the individual patient is known.
    Empagliflozin; Linagliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Empagliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
    Emtricitabine; Rilpivirine; Tenofovir disoproxil fumarate: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
    Enalapril; Felodipine: (Moderate) Concurrent use of felodipine and cobicistat should be approached with caution and conservative dosing of felodipine due to the potential for significant increases in felodipine exposure. Monitor for evidence of increased felodipine effects including decreased blood pressure and increased heart rate. Felodipine is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased felodipine AUC and half-life by approximately 8-fold and 2-fold, respectively.
    Encainide: (Moderate) The plasma concentrations of encainide may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while encainide is a CYP2D6 substrate.
    Encorafenib: (Major) Avoid coadministration of encorafenib and cobicistat due to increased encorafenib exposure. If concurrent use cannot be avoided, reduce the encorafenib dose to one-third of the dose used prior to the addition of cobicistat. If cobicistat is discontinued, the original encorafenib dose may be resumed after 3 to 5 elimination half-lives of cobicistat. Encorafenib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 50 mg dose of encorafenib (0.1 times the recommended dose) increased the encorafenib AUC and Cmax by 3-fold and 68%, respectively.
    Enfortumab vedotin: (Moderate) Closely monitor for signs of enfortumab vedotin-related adverse reactions if concurrent use with cobicistat is necessary. Concomitant use may increase unconjugated monomethyl auristatin E (MMAE) exposure, which may increase the incidence or severity of enfortumab-vedotin toxicities. MMAE, the microtubule-disrupting component of enfortumab vedotin, is a CYP3A4 and P-gp substrate; cobicistat is a dual P-gp/strong CYP3A4 inhibitor. Based on physiologically-based pharmacokinetic (PBPK) modeling predictions, concomitant use of enfortumab vedotin with another dual P-gp/strong CYP3A4 inhibitor is predicted to increase the exposure of unconjugated MMAE by 38%.
    Entrectinib: (Major) Avoid coadministration of entrectinib with cobicistat due to increased entrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided in adults and pediatric patients 12 years and older with BSA greater than 1.5 m2, reduce the entrectinib dose to 100 mg PO once daily. If cobicistat is discontinued, resume the original entrectinib dose after 3 to 5 elimination half-lives of cobicistat. Entrectinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of entrectinib by 6-fold in a drug interaction study.
    Enzalutamide: (Major) Coadministration of cobicistat with enzalutamide is not recommended as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is metabolized by CYP3A4; enzalutamide is a strong CYP3A4 inducer.
    Eplerenone: (Contraindicated) Eplerenone is contraindicated for use with cobicistat due to increased eplerenone exposure which increases the risk of developing hyperkalemia and hypotension. Cobicitat is a strong CYP3A4 inhibitor; eplerenone is a sensitive CYP3A4 substrate. Another strong CYP3A4 inhibitor increased serum eplerenone concentrations by roughly 5-fold.
    Erdafitinib: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
    Ergotamine: (Contraindicated) Coadministration of ergotamine with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
    Ergotamine; Caffeine: (Contraindicated) Coadministration of ergotamine with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
    Erlotinib: (Major) Avoid coadministration of erlotinib with cobicistat if possible due to the increased risk of erlotinib-related adverse reactions. If concomitant use is unavoidable and severe reactions occur, reduce the dose of erlotinib by 50 mg decrements. Erlotinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased erlotinib exposure by 67%.
    Ertugliflozin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Erythromycin: (Major) Avoid concurrent use of erythromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentations of erythromycin, cobicistat, atazanavir and darunavir. Erythromycin is a CYP3A4 inhibitor and a P-glycoprotein (P-gp) substrate. Cobicistat is a substrate of CYP3A4 and a P-gp inhibitor, while both atazanavir and daruanavir are CYP3A4 substrates.
    Erythromycin; Sulfisoxazole: (Major) Avoid concurrent use of erythromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentations of erythromycin, cobicistat, atazanavir and darunavir. Erythromycin is a CYP3A4 inhibitor and a P-glycoprotein (P-gp) substrate. Cobicistat is a substrate of CYP3A4 and a P-gp inhibitor, while both atazanavir and daruanavir are CYP3A4 substrates.
    Escitalopram: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Eslicarbazepine: (Major) In vivo studies suggest eslicarbazepine is an inducer of CYP3A4. Coadministration may result in significant decreases in the plasma concentrations of the CYP3A4 substrates, cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Consider use of an alternative anticonvulsant.
    Esomeprazole: (Minor) Use caution when administering cobicistat and esomeprazole concurrently. Cobicistat is an inhibitor of CYP3A, and esomeprazole is partially metabolized by CYP3A. Coadministration of cobicistat with CYP3A substrates, such as esomeprazole, can theoretically increase esomeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Estazolam: (Moderate) The plasma concentrations of estazolam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; estazolam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of estazolam. These drugs used in combination may result in elevated estazolam plasma concentrations, causing an increased risk for estazolam-related adverse events.
    Estradiol Cypionate; Medroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with medroxyprogesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Estradiol; Levonorgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Estradiol; Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Estradiol; Norgestimate: (Major) Concurrent administration of cobicistat and norgestimate results in increased norgestimate serum concentrations. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is also the potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Estradiol; Progesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with progesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. The metabolism of progesterone may also be inhibited by cobicistat, a strong inhibitor of the CYP3A4 hepatic enzyme. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin).
    Eszopiclone: (Major) The total dose of eszopiclone should not exceed 2 mg when administered with cobicistat. Coadministration may increase eszopiclone exposure resulting in increased risk of next-day psychomotor or memory impairment and decreased ability to perform tasks requiring full mental alertness such as driving. CYP3A4 is a primary metabolic pathway for eszopiclone; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased eszopiclone exposure by 2.2-fold.
    Ethinyl Estradiol: (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Ethinyl Estradiol; Norelgestromin: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norelgestromin. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Ethinyl Estradiol; Norethindrone Acetate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Ethinyl Estradiol; Norgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Ethosuximide: (Moderate) Close clinical monitoring is advised when administering ethosuximide with cobicistat. Coadministration may result in elevated ethosuximide plasma concentrations. Predictions regarding this interaction may be made based on the metabolic pathway of both drugs. Cobicistat is a strong inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of ethosuximide.
    Ethynodiol Diacetate; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with ethynodiol diacetate. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Etonogestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with etonogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Etonogestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with etonogestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Etravirine: (Major) Due to the potential for decreased antiretroviral efficacy and potential for adverse events, use of etravirine with cobicistat is not recommended. When these drugs are given together, the concentrations of cobicistat and etravirine may be decreased and increased, respectively. Both drugs are substrates for CYP3A4. Etravirine is also a CYP3A4 inducer, while cobicistat is a strong CYP3A4 inhibitor. Coadministration of etravirine with another strong CYP3A4 inhibitor increased etravirine exposure by 1.42-fold
    Everolimus: (Major) Avoid coadministration of everolimus with cobicistat due to the risk of increased everolimus-related adverse reactions. If concomitant use is unavoidable in patients receiving everolimus for either kidney or liver transplant, closely monitor everolimus whole blood trough concentrations. Everolimus is a sensitive CYP3A4 substrate and a P-glycoprotein (P-gp) substrate. Cobicistat is a strong CYP3A4 and P-gp inhibitor. Coadministration with another strong CYP3A4/P-gp inhibitor increased the AUC of everolimus by 15-fold.
    Ezetimibe; Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
    Fedratinib: (Major) Avoid coadministration of fedratinib with cobicistat as concurrent use may increase fedratinib exposure. If concurrent use cannot be avoided, reduce the dose of fedratinib to 200 mg PO once daily. If cobicistat is discontinued, increase the fedratinib dose as follows: 300 mg PO once daily for 2 weeks and then 400 mg PO once daily thereafter as tolerated. Fedratinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased fedratinib exposure by 3-fold.
    Felbamate: (Major) Coadministration of felbamate with cobicistat is not recommended. Concurrent use may decrease the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Felbamate is a CYP3A4 inducer, while cobicistat is a substrate of CYP3A4.
    Felodipine: (Moderate) Concurrent use of felodipine and cobicistat should be approached with caution and conservative dosing of felodipine due to the potential for significant increases in felodipine exposure. Monitor for evidence of increased felodipine effects including decreased blood pressure and increased heart rate. Felodipine is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concurrent use of another strong CYP3A4 inhibitor increased felodipine AUC and half-life by approximately 8-fold and 2-fold, respectively.
    Fentanyl: (Moderate) Consider a reduced dose of fentanyl with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the fentanyl dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Fentanyl is a CYP3A4 substrate, and coadministration with CYP3A4 inhibitors like cobicistat can increase fentanyl exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of fentanyl. If cobicistat is discontinued, fentanyl plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to fentanyl.
    Fesoterodine: (Major) Limit the dose of fesoterodine to 4 mg once daily in adults and pediatric patients weighing more than 35 kg if coadministered with cobicistat. Avoid use of fesoterodine and cobicistat in pediatric patients weighing 25 to 35 kg. Concurrent use may increase fesoterodine exposure. Fesoterodine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor led to approximately a doubling of the overall exposure of 5-hydroxymethyl tolterodine (5-HMT), the active metabolite of fesoterodine.
    Finerenone: (Contraindicated) Concomitant use of finerenone and cobicistat is contraindicated. Concomitant use may increase finerenone exposure and the risk for finerenone-related adverse reactions. Finerenone is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased overall exposure to finerenone by more than 400%.
    Flecainide: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of flecainide with cobicistat. Flecainide is a substrate for CYP2D6; cobicistat is an inhibitor of this enzyme. Concurrent use may result in elevated flecainde plasma concentration.
    Flibanserin: (Contraindicated) The concomitant use of flibanserin and strong CYP3A4 inhibitors such as cobicistat is contraindicated due to increased flibanserin concentrations, which can cause severe hypotension and syncope. If initiating flibanserin following the use of cobicistat, start flibanserin at least 2 weeks after the last dose of cobicistat. If initiating cobicistat following flibanserin use, begin therapy at least 2 days after the last dose of flibanserin. In cases where the benefit of initiating cobicistat therapy within 2 days of stopping flibanserin clearly outweighs the risk of flibanserin-related hypotension and syncope, monitor the patient for signs of hypotension and syncope.
    Fluconazole: (Moderate) Caution is warranted when cobicistat is administered with fluconazole as there is a potential for elevated cobicistat concentrations. Fluconazole is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
    Fluoxetine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Fluphenazine: (Moderate) Caution is warranted when cobicistat is administered with fluphenazine as there is a potential for elevated concentrations of fluphenazine and cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Fluphenazine and cobicistat are substrates and inhibitors of CYP2D6.
    Flurazepam: (Moderate) The plasma concentrations of flurazepam may be elevated when administered concurrently with cobicistat. Close clinical monitoring is recommended during coadministration; flurazepam dose reductions may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is a strong inhibitor of CYP3A4; inhibitors of this isoenzyme may reduce the metabolism of flurazepam and increase the potential for benzodiazepine toxicity.
    Flutamide: (Major) Caution is warranted when cobicistat is administered with flutamide as there is a potential for elevated flutamide concentrations and decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Flutamide is a substrate and inducer of CYP3A4. Cobicistat is a CYP3A4 substrate and inhibitor.
    Fluticasone: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate.
    Fluticasone; Salmeterol: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. (Major) Concurrent use of salmeterol with cobicistat is not recommended due to the potential for increased cardiovascular adverse events, such as QT prolongation, palpitations, and sinus tachycardia. Coadministration may result in elevated salmeterol serum concentrations.
    Fluticasone; Umeclidinium; Vilanterol: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
    Fluticasone; Vilanterol: (Major) Coadministration of inhaled fluticasone propionate and cobicistat is not recommended; use caution with inhaled fluticasone furoate. Increased systemic corticosteroid effects, including Cushing's syndrome and adrenal suppression, may occur. Fluticasone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with strong inhibitors increased plasma fluticasone exposure resulting in 45% to 86% decreases in serum cortisol AUC. A strong inhibitor increased fluticasone furoate exposure by 1.33-fold with a 27% reduction in weighted mean serum cortisol; this change does not necessitate dose adjustment of fluticasone furoate. (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
    Fluvastatin: (Major) The plasma concentrations of fluvastatin may increase when administered with cobicistat. Use the lowest starting dose of fluvastatin and carefully titrate while monitoring for adverse events.
    Fluvoxamine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Formoterol; Mometasone: (Moderate) Coadministration of mometasone with cobicistat may cause elevated mometasone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Mometasone is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Fosamprenavir: (Major) Coadministration of cobicistat with fosamprenavir is not recommended because pharmacokinetic data are not available to provide appropriate dosing recommendations. Cobicistat is not interchangeable with ritonavir as a boosting agent to fosamprenavir.
    Fosphenytoin: (Contraindicated) Coadministration of fosphenytoin with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Fostamatinib: (Moderate) Monitor for fostamatinib toxicities that may require fostamatinib dose reduction (i.e., elevated hepatic enzymes, neutropenia, high blood pressure, severe diarrhea) if given concurrently with a strong CYP3A4 inhibitor. Concomitant use of fostamatinib with a strong CYP3A4 inhibitor increases exposure to the major active metabolite, R406, which may increase the risk of adverse reactions. R406 is extensively metabolized by CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration of fostamatinib with another strong CYP3A4 inhibitor increased R406 AUC by 102% and Cmax by 37%.
    Gefitinib: (Moderate) Monitor for an increase in gefitinib-related adverse reactions if coadministration with cobicistat is necessary. Gefitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased gefitinib exposure by 80%.
    Gilteritinib: (Major) Consider an alternative to cobicistat during treatment with gilteritinib. Concurrent use may increase gilteritinib exposure resulting in treatment-related adverse events. If coadministration is required, frequently monitor for gilteritinib adverse reactions. Interrupt therapy and reduce the gilteritinib dose if serious or life-threatening toxicity occurs. Gilteritinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the gilteritinib AUC by 120% in a drug interaction study.
    Glasdegib: (Major) Consider an alternative to cobicistat during treatment with glasdegib. Concurrent use may increase glasdegib exposure resulting in treatment-related adverse events including QT prolongation. If coadministration cannot be avoided, monitor for increased adverse events; more frequent ECG monitoring is recommended. Glasdegib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the glasdegib AUC by 2.4-fold in a drug interaction study.
    Glecaprevir; Pibrentasvir: (Moderate) Caution is advised with the coadministration of glecaprevir and cobicistat as coadministration may increase serum concentrations of glecaprevir and increase the risk of adverse effects. Glecaprevir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP) 1B1/3, and breast cancer resistance protein (BCRP); cobicistat is an inhibitor of all these transporters. (Moderate) Caution is advised with the coadministration of pibrentasvir and cobicistat as coadministration may increase serum concentrations of pibrentasvir and increase the risk of adverse effects. Pibrentasvir is a substrate of of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP); cobicistat is an inhibitor of P-gp and BCRP.
    Glipizide; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Glyburide: (Moderate) Caution is warranted when cobicistat is administered with glyburide as there is a potential for elevated glyburide concentrations. Glyburide is a substrate of P-glycoprotein (P-gp) and cobicistat is an inhibitor of P-gp.
    Glyburide; Metformin: (Moderate) Caution is warranted when cobicistat is administered with glyburide as there is a potential for elevated glyburide concentrations. Glyburide is a substrate of P-glycoprotein (P-gp) and cobicistat is an inhibitor of P-gp. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Granisetron: (Minor) Plasma concentrations of granisetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while granisetron is a CYP3A4 substrate.
    Grapefruit juice: (Moderate) Caution is warranted when cobicistat is administered with grapefruit juice as there is a potential for elevated cobicistat concentrations. Grapefruit juice is a CYP3A4 and CYP2D6 inhibitor, while cobicistat is a substrate of CYP3A4 and CYP2D6.
    Guaifenesin; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Guanfacine: (Major) If coadministration of cobicistat with extended-release (ER) guanfacine is necessary, reduce the guanfacine dosage to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available. Monitor patients closely for alpha-adrenergic effects including hypotension, drowsiness, lethargy, and bradycardia. If cobicstat is discontinued, the guanfacine ER dosage should be increased back to the recommended dose. Guanfacine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Cobicstast may significantly increase guanfacine plasma concentrations.
    Haloperidol: (Moderate) Caution is warranted when cobicistat is administered with haloperidol as there is a potential for elevated haloperidol concentrations. Haloperidol is a CYP3A4 substrate and CYP2D6 substrate. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6.
    Homatropine; Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone; Ibuprofen: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone; Phenylephrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone; Potassium Guaiacolsulfonate: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydrocodone; Pseudoephedrine: (Moderate) Consider a reduced dose of hydrocodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. It is recommended to avoid this combination when hydrocodone is being used for cough. Hydrocodone is a CYP2D6 and CYP3A4 substrate, and coadministration with CYP2D6 and CYP3A4 inhibitors like cobicistat can increase hydrocodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of hydrocodone. These effects could be more pronounced with a combined CYP2D6 and CYP3A4 inhibitor. If cobicistat is discontinued, hydrocodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to hydrocodone.
    Hydroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with hydroxyprogesterone caproate. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Ibrexafungerp: (Major) Decrease the ibrexafungerp dose to 150 mg PO every 12 hours for 1 day if administered concurrently with cobicistat. Coadministration may result in increased ibrexafungerp exposure and toxicity. Ibrexafungerp is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the AUC and Cmax of ibrexafungerp by 5.8-fold and 2.5-fold, respectively.
    Ibrutinib: (Major) Avoid concomitant use of ibrutinib and cobicistat; ibrutinib plasma concentrations may increase resulting in severe ibrutinib toxicity (e.g., hematologic toxicity, bleeding, infection). Ibrutinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased ibrutinib exposure by 5.7-fold to 24-fold.
    Ibuprofen; Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
    Idelalisib: (Major) Coadministration of idelalisib with cobicistat may increase the exposure of both drugs; avoid use and use alternative agents if possible. Both drugs are CYP3A4 substrates and strong CYP3A4 inhibitors. If use of both drugs is required, monitor for idelalisib- and cobicistat-related adverse reactions. Coadministration with a strong CYP3A inhibitor increased idelalisib expoure by 1.8-fold.
    Ifosfamide: (Moderate) Monitor for a decrease in the efficacy of ifosfamide if coadministration with cobicistat is necessary. Ifosfamide is metabolized by CYP3A4 to its active alkylating metabolites. Cobicistat is a strong CYP3A4 inhibitor. Coadministration may decrease plasma concentrations of these active metabolites, decreasing the effectiveness of ifosfamide treatment.
    Iloperidone: (Major) Reduce the iloperidone dose by one-half if coadministered with cobicistat If chloramphenicol is discontinued, increase the iloperidone dose to the previous level. Increased iloperidone exposure may occur with concurrent use. Iloperidone is a CYP3A4 substrate. Chloramphenicol is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of iloperidone and its metabolites P88 and P95 by 57%, 55% and 35%, respectively.
    Imatinib: (Moderate) Caution is warranted when cobicistat is administered with imatinib, STI-571 as there is a potential for elevated imatinib and/or cobicistat concentrations. Imatinib is a CYP3A4 substrate and moderate iinhibitor, a weak inhibitor of CYP2D6, and a breast cancer resistance protein (BCRP) substrate. Cobicistat is a strong inhibitor of CYP3A4, a BCRP inhibitor, and a substrate of CYP2D6 and CYP3A4. Coadministration of imatinib with another strong CYP3A4 inhibitor increased imatinib exposure by 40%.
    Imipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Indacaterol: (Moderate) Clinical monitoring for adverse effects, such as headache, nervousness, tremor, or cardiovascular effects, is recommended during coadministration. Plasma concentrations of indacaterol may be elevated when administered concurrently with cobicistat. Cobicistat is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) inhibitor, while indacaterol is a CYP3A4, CYP2D6, and P-gp substrate. Coadministration with other dual inhibitors of CYP3A4 and P-gp has increased exposure of indacaterol from 1.4- to 1.9- fold.
    Indacaterol; Glycopyrrolate: (Moderate) Clinical monitoring for adverse effects, such as headache, nervousness, tremor, or cardiovascular effects, is recommended during coadministration. Plasma concentrations of indacaterol may be elevated when administered concurrently with cobicistat. Cobicistat is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) inhibitor, while indacaterol is a CYP3A4, CYP2D6, and P-gp substrate. Coadministration with other dual inhibitors of CYP3A4 and P-gp has increased exposure of indacaterol from 1.4- to 1.9- fold.
    Indinavir: (Contraindicated) Concomitant use of indinavir with regimens containing cobicistat and atazanavir is contraindicated. Cobicistat is an inhibitor of CYP3A4, while both atazanavir and indinavir are CYP3A4 substates. In addition, both atazanavir and indinavir are associated with indirect (unconjugated) hyperbilirubinemia. Taking these drugs together may increase the risk for hepatic adverse events, such as hyperbilirubinemia.
    Infigratinib: (Major) Avoid concomitant use of infigratinib and cobicistat. Coadministration may increase infigratinib exposure, increasing the risk for adverse effects. Infigratinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the AUC of infigratinib by 622%.
    Irinotecan Liposomal: (Contraindicated) Discontinue use of antiretroviral regimens containing cobicistat at least 1 week prior to starting irinotecan. Concurrent use of irinotecan with cobicistat 'boosted' atazanavir is contraindicated; however, irinotecan may be used with other cobicistat-containing regimens if no other therapeutic alternatives are available. If these drugs are administered concurrently, monitor for increased irinotecan side effects, including diarrhea, nausea, vomiting, and myelosuppression. Cobicistat is a strong CYP3A4 and P-glycoprotein (P-gp) inhibitor; irinotecan is a CYP3A4 and P-gp substrate. Exposure to irinotecan and to the active metabolite, SN-38, will increase when these drugs are used together.
    Irinotecan: (Contraindicated) Discontinue use of antiretroviral regimens containing cobicistat at least 1 week prior to starting irinotecan. Concurrent use of irinotecan with cobicistat 'boosted' atazanavir is contraindicated; however, irinotecan may be used with other cobicistat-containing regimens if no other therapeutic alternatives are available. If these drugs are administered concurrently, monitor for increased irinotecan side effects, including diarrhea, nausea, vomiting, and myelosuppression. Cobicistat is a strong CYP3A4 and P-glycoprotein (P-gp) inhibitor; irinotecan is a CYP3A4 and P-gp substrate. Exposure to irinotecan and to the active metabolite, SN-38, will increase when these drugs are used together.
    Isavuconazonium: (Contraindicated) Coadministration of isavuconazonium with cobicistat is contraindicated due to the risk of increased isavuconazole exposure. Isavuconazole is a sensitive substrate of CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased isavuconazole exposure by 422%.
    Isoniazid, INH: (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
    Isoniazid, INH; Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. (Moderate) Caution is warranted when cobicistat is administered with isoniazid, INH as there is a potential for elevated cobicistat concentrations. Isoniazid is a CYP3A4 inhibitor, while cobicistat is a substrate of CYP3A4.
    Isradipine: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as isradipine, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate reductions are advised.
    Istradefylline: (Major) Do not exceed 20 mg once daily of istradefylline if administered with cobicistat as istradefylline exposure and adverse effects may increase. Cobicistat is a strong CYP3A4 inhibitor. Istradefylline exposure was increased by 2.5-fold when administered with a strong inhibitor in a drug interaction study.
    Itraconazole: (Major) Avoid concurrent use of itraconazole with regimens containing cobicistat and atazanavir or darunavir. Use of these drugs together may result in increased plasma concentrations of itraconazole, cobicistat, atazanavir, and darunavir. Specific dosage recommendations have not been determined.
    Ivabradine: (Contraindicated) Coadministration of cobicistat with ivabradine is contraindicated due to an increase in plasma concentrations of ivabradine, which may exacerbate bradycardia and conduction disturbances. Ivabradine is primarily metabolized by CYP3A4; cobicistat is a strong inhibitor of CYP3A4. Coadministration with another strong CYP3A4 inhibitor increased ivabradine exposure by 7.7-fold.
    Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold.
    Ivosidenib: (Major) Avoid coadministration of ivosidenib with cobicistat due to increased plasma concentrations of ivosidenib, which increases the risk of QT prolongation. If concomitant use is unavoidable, reduce the dose of ivosidenib to 250 mg PO once daily. Monitor ECGs for QTc prolongation and monitor electrolytes, correcting any electrolyte abnormalities as clinically appropriate. If cobicistat is discontinued, wait at least 5 half-lives of cobicistat before increasing the dose of ivosidenib to the recommended dose of 500 mg PO once daily. Ivosidenib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ivosidenib single-dose AUC to 269% of control, with no change in Cmax.
    Ixabepilone: (Major) Avoid coadministration of cobicistat with ixabepilone if possible due to increased ixabepilone exposure. If concomitant use is unavoidable, consider reducing the dose of ixabepilone to 20 mg/m2. If cobicistat is discontinued, resume the original dose of ixabepilone after a washout period of approximately 1 week. Cobicistat is a strong CYP3A4 inhibitor and a P-glycoprotein (P-gp) inhibitor, while ixabepilone is a CYP3A4 and P-gp substrate. Coadministration with another strong CYP3A4 inhibitor increased ixabepilone exposure by 79%.
    Ketoconazole: (Major) Avoid concurrent use of ketoconazole with regimens containing cobicistat and atazanavir or darunavir. Use of these drugs together may result in increase plasma concentrations of ketoconazole, cobicistat, atazanavir, and darunavir. Specific dosage recommendations have not been determined.
    Lansoprazole: (Minor) Use caution when administering cobicistat and lansoprazole concurrently. Cobicistat is an inhibitor of CYP3A. Coadministration of cobicistat with CYP3A substrates, such as lansoprazole, can increase lansoprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Lansoprazole; Amoxicillin; Clarithromycin: (Major) Avoid concurrent use of clarithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentrations of clarithromycin, cobicistat, atazanavir and darunavir. Both clarithromycin and cobicistat are inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir. (Minor) Use caution when administering cobicistat and lansoprazole concurrently. Cobicistat is an inhibitor of CYP3A. Coadministration of cobicistat with CYP3A substrates, such as lansoprazole, can increase lansoprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Lansoprazole; Naproxen: (Minor) Use caution when administering cobicistat and lansoprazole concurrently. Cobicistat is an inhibitor of CYP3A. Coadministration of cobicistat with CYP3A substrates, such as lansoprazole, can increase lansoprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Lapatinib: (Major) Avoid coadministration of lapatinib with cobicistat due to increased plasma concentrations of lapatinib. If concomitant use is unavoidable, decrease the dose of lapatinib to 500 mg PO once daily. If cobicistat is discontinued, increase lapatinib to the indicated dose after a washout period of approximately 1 week. Lapatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Concomitant use with another strong CYP3A4 inhibitor increased lapatinib exposure by 3.6-fold and increased the half-life of lapatinib by 1.7-fold.
    Larotrectinib: (Major) Avoid coadministration of larotrectinib with cobicistat due to increased larotrectinib exposure resulting in increased treatment-related adverse effects. If coadministration cannot be avoided, reduce the larotrectinib dose by 50%. If cobicistat is discontinued, resume the original larotrectinib dose after 3 to 5 elimination half-lives of cobicistat. Larotrectinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor increased the AUC of larotrectinib by 4.3-fold in a drug interaction study.
    Ledipasvir; Sofosbuvir: (Moderate) Caution is warranted when cobicistat is administered with ledipasvir; sofosbuvir as there is a potential for elevated concentrations of ledipasvir and sofosbuvir. Cobicistat is an inhibitor of the transporters P-glycoprotein and breast cancer resistance protein (BCRP). Both ledipasvir and sofosbuvir are substrates of P-gp and BCRP. According to the manufacturer, no dosage adjustments are required when ledipasvir; sofosbuvir is administered concurrently with P-gp or BCRP inhibitors; however, if these drugs are given together, consider increased monitoring for potential adverse effect (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP.
    Lefamulin: (Major) Avoid coadministration of cobicistat with oral lefamulin due to increased lefamulin exposure; cobicistat may be administered with intravenous lefamulin. Lefamulin is a CYP3A4 and P-gp substrate; cobicistat is a P-gp and strong CYP3A4 inhibitor. Coadministration of a combined P-gp and strong CYP3A4 inhibitor increased the exposure of oral and intravenous lefamulin by 165% and 31%, respectively.
    Lemborexant: (Major) Avoid coadministration of lemborexant and cobicistat as concurrent use is expected to significantly increase lemborexant exposure and the risk of adverse effects. Lemborexant is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of lemborexant with another strong CYP3A4 inhibitor increased the lemborexant AUC by up to 4.5-fold.
    Letermovir: (Moderate) Administering cobicistat concurrently with letermovir may result in increased concentrations of both drugs. The impact on the concentration of cobicistat may be increased in patients who are receiving letermovir with cyclosporine. Closely monitor for adverse events, including tachycardia, atrial fibrillation, and gastrointestinal events. Cobicistat is an inhibitor of the organic anion-transporting polypeptides (OATP1B1/3), and a substrate of CYP3A4. Letermovir is an OATP1B1/3 substrate and a moderate CYP3A4 inhibitor. When given with cyclosporine, the combined effect of letermovir and cyclosporine on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor.
    Leuprolide; Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Levamlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Levomilnacipran: (Major) Do not exceed a levomilnacipran dose of 80 mg once daily if coadministration with cobicistat is necessary. Levomilnacipran is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased levomilnacipran exposure by about 50%.
    Levonorgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Levonorgestrel; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with levonorgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Lidocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Lidocaine; Prilocaine: (Moderate) Monitor for lidocaine-related adverse reactions if coadministration with cobicistat is necessary. Lidocaine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Linagliptin; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Lomitapide: (Contraindicated) Concomitant use of cobicistat and lomitapide is contraindicated due to the potential of markedly increased lomitapide concentrations and the associated elevation of serum transaminases. Cobicistat is a strong CYP3A4 inhibitor. The exposure to lomitapide was increased 27-fold in the presence another strong CYP3A4 inhibitor.
    Lonafarnib: (Contraindicated) Coadministration of lonafarnib and cobicistat is contraindicated; concurrent use may increase the exposure of both drugs and the risk of adverse effects. Lonafarnib is a sensitive CYP3A4 substrate and strong CYP3A4 inhibitor; cobicistat is a CYP3A4 substrate and strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of lonafarnib by 425%.
    Loperamide: (Moderate) The plasma concentration of loperamide, a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) substrate, may be increased when administered concurrently with cobicistat, an inhibitor of CYP3A4, CYP2D6, and P-gp. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Loperamide; Simethicone: (Moderate) The plasma concentration of loperamide, a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) substrate, may be increased when administered concurrently with cobicistat, an inhibitor of CYP3A4, CYP2D6, and P-gp. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Lopinavir; Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4.
    Lorcaserin: (Moderate) Caution is warranted when cobicistat is administered with lorcaserin as there is a potential for elevated cobicistat concentrations. Lorcaserin is a CYP2D6 inhibitor. Cobicistat is a substrate of CYP2D6.
    Lorlatinib: (Major) Avoid coadministration of lorlatinib with cobicistat due to increased plasma concentrations of lorlatinib, which may increase the incidence and severity of adverse reactions of lorlatinib; plasma concentrations of cobicistat may also decrease. If concomitant use is unavoidable, reduce the starting dose of lorlatinib from 100 mg to 75 mg once daily, or from 75 mg to 50 mg once daily. If cobicistat is discontinued, resume the original dose of lorlatinib after 3 half-lives of cobicistat. Lorlatinib is a CYP3A4 substrate and a moderate CYP3A4 inducer. Cobicistat is a CYP3A4 substrate and a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased lorlatinib exposure by 42%. Coadministration of cobicistat with moderate CYP3A4 inducers may reduce antiretroviral efficacy and increase the potential development of viral resistance.
    Losartan: (Minor) Caution is warranted when cobicistat is administered with losartan as there is a potential for increased losartan concentrations. Losartan is a substrate of CYP3A4; cobicistat is an inhibitor of CYP3A4.
    Losartan; Hydrochlorothiazide, HCTZ: (Minor) Caution is warranted when cobicistat is administered with losartan as there is a potential for increased losartan concentrations. Losartan is a substrate of CYP3A4; cobicistat is an inhibitor of CYP3A4.
    Lovastatin: (Contraindicated) Concomitant use of lovastatin with cobicistat is contraindicated due to the potential for myopathy, including rhabdomyolysis. Coadministration is expected to significantly increase lovastatin plasma concentrations. Lovastatin is a substrate for CYP3A4; cobicistat is a strong inhibitor of CYP3A. Coadministration with another strong CYP3A4 inhibitor increased lovastatin exposure by 11 to 36-fold.
    Lovastatin; Niacin: (Contraindicated) Concomitant use of lovastatin with cobicistat is contraindicated due to the potential for myopathy, including rhabdomyolysis. Coadministration is expected to significantly increase lovastatin plasma concentrations. Lovastatin is a substrate for CYP3A4; cobicistat is a strong inhibitor of CYP3A. Coadministration with another strong CYP3A4 inhibitor increased lovastatin exposure by 11 to 36-fold.
    Lumacaftor; Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold.
    Lumacaftor; Ivacaftor: (Major) Lumacaftor; ivacaftor may decrease the therapeutic efficacy of cobicistat; avoid concurrent use if possible. If concomitant use of cobicistat is necessary, monitor antiretroviral efficacy, consider the use of therapeutic drug monitoring, and adjust drug dosages as necessary. Lumacaftor; ivacaftor dosage adjustment is not required when cobicistat is started in a patient already taking lumacaftor; ivacaftor. However, if lumacaftor; ivacaftor is initiated in a patient already taking cobicistat, reduce the dose of lumacaftor; ivacaftor to 1 tablet PO daily or 1 packet of oral granules every other day for the first week of treatment, and then increase to the usual recommended daily dose. This dosage adjustment is also necessary if lumacaftor; ivacaftor therapy has been interrupted for more than 1 week and re-initiated while the patient is taking cobicistat. The 1-week lead-in period at the lower lumacaftor; ivacaftor dosage allows for lumacaftor's induction of CYP3A to reach steady state. Cobicistat is a substrate and strong inhibitor of CYP3A. Ivacaftor is a CYP3A substrate, and lumacaftor is a strong CYP3A inducer. Lumacaftor's induction of CYP3A may decrease the systemic exposure of cobicistat and decrease its therapeutic efficacy. Although cobicistat is a strong CYP3A4 inhibitor, net ivacaftor exposure at steady state is not expected to exceed that achieved with ivacaftor monotherapy (i.e., 150 mg PO every 12 hours) because of lumacaftor's CYP3A induction. In pharmacokinetic studies, coadministration of lumacaftor; ivacaftor with another strong CYP3A4 inhibitor increased ivacaftor exposure by 4.3-fold.
    Lumateperone: (Major) Avoid coadministration of lumateperone and cobicistat as concurrent use may increase lumateperone exposure and the risk of adverse effects. Lumateperone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased lumateperone exposure by approximately 4-fold.
    Lurasidone: (Contraindicated) Coadministration of cobicistat (or cobicistat containing medications) with lurasidone is contraindicated due to the potential for serious or life-threatening reactions, such as CNS effects and extrapyramidal symptoms. The plasma concentrations of lurasidone may be elevated when administered concurrently with cobicistat. Cobicistat is a strong CYP3A4 inhibitor, while lurasidone is a sensitive CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased lurasidone exposure by 9-fold.
    Lurbinectedin: (Major) Avoid coadministration of lurbinectedin and cobicistat due to the risk of increased lurbinectedin exposure which may increase the incidence of lurbinectedin-related adverse reactions. Lurbinectedin is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor.
    Macitentan: (Major) Avoid coadministration of macitentan with cobicistat due to increased plasma concentrations of macitentan. Macitentan is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased macitentan exposure by approximately 2.3-fold.
    Maprotiline: (Major) The plasma concentrations of maprotiline may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Maprotiline serum concentration monitoring may be useful to guide dosage adjustments and prevent toxicity. Cobicistat is a CYP2D6 inhibitor, while maprotiline is a CYP2D6 substrate.
    Maraviroc: (Major) Coadministration of maraviroc (a substrate of CYP3A, P-gp, and OATP1B1) with cobicistat (a CYP3A4, P-gp, OATP1B1 inhibitor) may result in increased maraviroc concentrations. Reduce the dose of maraviroc when coadministered with cobicistat; coadministration is contraindicated in patients with CrCl less than 30 mL/min. Adjust the maraviroc dosage as follows when administered with cobicistat (with or without a concomitant CYP3A inducer): adults and children weighing 40 kg or more: 150 mg PO twice daily; children weighing 30 to 39 kg: 100 mg PO twice daily; children weighing 20 to 29 kg: 75 mg PO twice daily (or 80 mg PO twice daily for solution); children weighing 10 to 19 kg: 50 mg PO twice daily; children weighing 2 to 9 kg: use not recommended.
    Meclizine: (Moderate) The plasma concentrations of meclizine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while meclizine is a CYP2D6 substrate.
    Medroxyprogesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with medroxyprogesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Mefloquine: (Moderate) The plasma concentrations of mefloquine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or neurophsychiatric effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and P-glycoprotein (P-gp) inhibitor, while mefloquine is a CYP3A4 and P-gp substrate.
    Meperidine; Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
    Mestranol; Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol or mestranol (converted to ethinyl estradiol). There are data to suggest that cobicistat reduces ethinyl estradiol concentrations, which may lead to reduced effectiveness of combined hormonal contraceptive products, or, reduced efficacy of hormone replacement therapy (HRT). Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking HRT, monitor for reduced efficacy such as increased hot flash frequency or unusual vaginal bleeding patterns,
    Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Metformin; Repaglinide: (Moderate) Coadministration of repaglinide and cobicistat may increase plasma concentrations of repaglinide; if coadministration is necessary, repaglinide dosage adjustment may be required and an increased frequency of glucose monitoring is recommended. Cobicistat is a strong CYP3A4 inhibitor and an inhibitor of organic anion transporting polypeptide (OATP). Repaglinide is a CYP3A4 and OATP1B1 substrate. Coadministration with other strong CYP3A4 inhibitors increased repaglinide exposure by up to 1.5-fold. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Metformin; Rosiglitazone: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Metformin; Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively. (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Metformin; Sitagliptin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Methadone: (Moderate) The plasma concentrations of methadone may be elevated when administered concurrently with cobicistat. When initiating methadone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest methadone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on methadone, an adjustment of methadone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Methadone is metabolized primarily by the cytochrome P450 isoenzymes CYP2C19, CYP3A4, and CYP2B6, and to a lesser extent, by CYP2C9 and CYP2D6. Methadone also is a substrate of P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp.
    Methamphetamine: (Moderate) The plasma concentrations of methamphetamine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while methamphetamine is a CYP2D6 substrate.
    Methylergonovine: (Contraindicated) Coadministration of methylergonovine with cobicistat is contraindicated. Cobicistat is an inhibitor of CYP3A, and plasma concentrations of drugs extensively metabolized by this enzyme, such as ergot alkaloids, are expected to increase with concurrent use. Elevated plasma concentrations of ergot alkaloids are associated with risk of acute ergot toxicity which is characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
    Methylprednisolone: (Moderate) Coadministration of methylprednisolone with cobicistat may cause elevated methylprednisolone serum concentrations, potentially resulting in Cushing's syndrome or adrenal suppression. Cobicistat is a CYP3A4 inhibitor, while methylprednisolone is a CYP3A4 substrate. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Metoclopramide: (Moderate) Caution is warranted when cobicistat is administered with metoclopramide as there is a potential for elevated metoclopramide and cobicistat concentrations. Metoclopramide is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
    Metoprolol: (Moderate) Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration. A dosage reduction for metoprolol may be needed based on response. Concurrent use may increase metoprolol exposure. Metoprolol is a CYP2D6 substrate; cobicistat is a weak CYP2D6 inhibitor.
    Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration. A dosage reduction for metoprolol may be needed based on response. Concurrent use may increase metoprolol exposure. Metoprolol is a CYP2D6 substrate; cobicistat is a weak CYP2D6 inhibitor.
    Mexiletine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of mexiletine with cobicistat. Mexiletine is a substrate for CYP2D6; cobicistat is an inhibitor of this enzyme. Concurrent use may result in elevated mexiletine plasma concentration.
    Midazolam: (Major) Use of orally administered midazolam with cobicistat is contraindicated due to the risk for prolonged/increased sedation and respiratory depression. Midazolam is extensively metabolized by CYP3A4; cobicistat is a strong inhibitor of this enzyme. Concurrent use is expected to produce large increases in the plasma concentrations of midazolam. Elevations in midazolam concentrations may also be observed with the parenteral formulation of midazolam; however, this formulation may be administered with cobicistat if given in as setting with close clinical monitoring and appropriate medical management. Consider reducing the dose of parenteral midazolam.
    Midostaurin: (Major) Avoid the concomitant use of midostaurin and cobicistat as significantly increased exposure of midostaurin and its active metabolites may occur resulting in increased toxicity. Consider an alternative agent to replace cobicistat. If coadministration cannot be avoided, monitor patients for signs and symptoms of midostaurin toxicity (e.g., gastrointestinal toxicity, hematologic toxicity, bleeding, and infection), particularly during the first week of midostaurin therapy for systemic mastocytosis/mast cell leukemia and the first week of each cycle of midostaurin therapy for acute myeloid leukemia. Midostaurin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. The AUC values of midostaurin and its metabolites CGP62221 and CGP52421 increased by 10.4-fold, 3.5-fold, and 1.2-fold, respectively, when midostaurin was administered with another strong CYP3A4 inhibitor in a drug interaction study. The Cmin (trough) levels of midostaurin and its metabolites CGP62221 and CGP52421 on day 28 increased by 2.1-fold, 1.2-fold, and 1.3-fold, respectively, when midostaurin was administered with another strong CYP3A4 inhibitor compared with day 21 Cmin levels with midostaurin alone in another drug interaction study.
    Mifepristone: (Major) Caution is advised when administering cobicistat with mifepristone because increased serum concentrations of either drug may occur. When mifepristone is used in the treatment of Cushing's syndrome, coadministration with cobicistat should be done only when necessary, and in such cases the dose of mifepristone should be limited to a maximum dose of 900 mg per day. In a patient already receiving cobicistat, initiate mifepristone at a dose of 300 mg and titrate to a maximum of 900 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving mifepristone 300 mg, dosage adjustments are not required. If therapy with cobicistat is initiated in a patient already receiving mifepristone 600 mg, reduce dose of mifepristone to 300 mg and titrate to a maximum of 600 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving 900 mg, reduce dose of mifepristone to 600 mg and titrate to a maximum of 900 mg if clinically indicated. If therapy with cobicistat is initiated in a patient already receiving 1,200 mg, reduce the mifepristone dose to 900 mg. Both mifepristone and cobicistat are substrates and strong inhibitors of CYP3A4.
    Mirabegron: (Moderate) Caution is warranted when cobicistat is administered with mirabegron as there is a potential for elevated cobicistat concentrations. Mirabegron is a moderate CYP2D6 inhibitor. Cobicistat is a substrate of CYP2D6 and CYP3A4.
    Mirtazapine: (Moderate) The plasma concentrations of mirtazapine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS or GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor and an inhibitor of CYP2D6, while mirtazapine is a CYP3A4 and CYP2D6 substrate. Coadministration with another strong CYP3A4 inhibitor increased mirtazapine exposure by approximately 50%
    Mitotane: (Contraindicated) Coadministration of mitotane with cobicistat is contraindicated. Mitotane is a strong inducer of CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
    Mobocertinib: (Major) Avoid concomitant use of mobocertinib and cobicistat. Concomitant use may increase mobocertinib exposure and the risk for adverse reactions such as QT prolongation. Mobocertinib is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Use of a strong CYP3A inhibitor is predicted to increase the overall exposure of mobocertinib and its active metabolites by 374% to 419%.
    Modafinil: (Major) Coadministration of cobicistat with modafinil is not recommended as there is a potential for elevated modafinil concentrations and decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Modafinil is a CYP3A4 substrate/inducer. Cobicistat is an inhibitor/substrate of CYP3A4.
    Mometasone: (Moderate) Coadministration of mometasone with cobicistat may cause elevated mometasone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Mometasone is a CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Morphine: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Morphine; Naltrexone: (Moderate) The plasma concentrations of morphine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as oversedation, respiratory depression, and hypotension, is recommended during coadministration. Cobicistat is a P-glycoprotein (P-gp) inhibitor, while morphine is a P-gp substrate.
    Nafcillin: (Major) Caution is warranted when cobicistat is administered with nafcillin as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Nafcillin is an inducer of CYP3A4. Cobicistat is a CYP3A4 substrate.
    Naldemedine: (Moderate) Monitor for potential naldemedine-related adverse reactions if coadministered with cobicistat. The plasma concentrations of naldemedine may be increased during concurrent use. Naldemedine is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a moderate P-gp inhibitor and strong CYP3A4 inhibitor.
    Naloxegol: (Contraindicated) Concomitant use of naloxegol with cobicistat is contraindicated. Naloxegol is metabolized primarily by CYP3A. Strong CYP3A4 inhibitors, such as cobicistat, can significantly increase exposure to naloxegol which may precipitate opioid withdrawal symptoms such as hyperhidrosis, chills, diarrhea, abdominal pain, anxiety, irritability, and yawning.
    Naloxone: (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
    Nanoparticle Albumin-Bound Paclitaxel: (Moderate) Monitor for an increase in paclitaxel-related adverse reactions if coadministration of nab-paclitaxel with cobicistat is necessary due to the risk of increased plasma concentrations of paclitaxel. Nab-paclitaxel is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. In vitro, coadministration with both strong and moderate CYP3A4 inhibitors increased paclitaxel exposure; however, the concentrations used exceeded those found in vivo following normal therapeutic doses. The pharmacokinetics of paclitaxel may also be altered in vivo as a result of interactions with CYP3A4 inhibitors.
    Nanoparticle Albumin-Bound Sirolimus: (Major) Avoid coadministration of sirolimus with cobicistat if possible due to increased plasma concentrations of sirolimus resulting in treatment-related adverse reactions. Sirolimus is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Naproxen; Esomeprazole: (Minor) Use caution when administering cobicistat and esomeprazole concurrently. Cobicistat is an inhibitor of CYP3A, and esomeprazole is partially metabolized by CYP3A. Coadministration of cobicistat with CYP3A substrates, such as esomeprazole, can theoretically increase esomeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Nebivolol: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with cobicistat. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as cobicistat, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible.
    Nebivolol; Valsartan: (Moderate) Monitor for increased toxicity as well as increased therapeutic effect of nebivolol if coadministered with cobicistat. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as cobicistat, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Nefazodone: (Moderate) Caution is warranted when cobicistat is administered with nefazodone as there is a potential for elevated nefazodone and cobicistat concentrations. Both nefazodone and cobicistat are substrates and strong inhibitors of CYP3A4.
    Neratinib: (Major) Avoid concomitant use of cobicistat with neratinib due to an increased risk of neratinib-related toxicity. Neratinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased neratinib exposure by 381%; concomitant use with other strong inhibitors of CYP3A4 may also increase neratinib concentrations.
    Netupitant, Fosnetupitant; Palonosetron: (Moderate) Netupitant is a moderate inhibitor of CYP3A4 and should be used with caution in patients receiving concomitant medications that are primarily metabolized through CYP3A4, such as cobicistat. The plasma concentrations of cobicistat can increase when co-administered with netupitant; the inhibitory effect on CYP3A4 can last for multiple days. In addition, netupitant is mainly metabolized by CYP3A4. Cobicistat has been shown to be a strong CYP3A4 inhibitor, and may increase netupitant exposure. Coadministration with another strong CYP3A4 inhibitor increased netupitant exposure by 140%. No dosage adjustment is necessary. (Moderate) The plasma concentrations of palonosetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is an inhibitor of CYP3A4 and CYP2D6; palonosetron is a substrate of both CYP3A4 and CYP2D6.
    Nevirapine: (Contraindicated) Coadministration of nevirapine with regimens containing cobicistat and atazanavir are contraindicated; use of nevirapine with regimens containing cobicistat and darunavir are also not recommended. Nevirapine is a substrate and inducer of CYP3A4, cobicistat is a substrate/inhibitor of CYP3A4, while atazanavir are darunavir are CYP3A4 substrates. If these drugs are used together, the concentrations of nevirapine may increase and the concentrations of atazanavir, darunavir, and cobicistat may decrease; thereby, increasing the risk for nevirapine-associated adverse reactions and potentally decreasing the antiretroviral efficacy of atazanavir and darunavir.
    Niacin; Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
    Nicardipine: (Moderate) Coadministration of cobicistat with nicardipine may result in elevated cobicistat serum concentrations. Cobicistat is a substrate of CYP3A4 and CYP2D6. Nicardipine is an inhibitor of CYP2D6 and CYP3A4.
    Nicotine: (Minor) Caution is warranted when cobicistat is administered with nicotine as there is a potential for decreased cobicistat concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Nicotine is an inducer of CYP2D6; cobicistat is a CYP2D6 substrate.
    Nifedipine: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as nifedipine, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate reductions are advised.
    Nilotinib: (Major) Avoid the concomitant use of nilotinib and cobicistat. If coadministration is required, monitor patients closely for prolongation of the QT interval and reduce the nilotinib dose to 300 mg once daily in patients with resistant or intolerant Ph+ CML or to 200 mg once daily in patients with newly diagnosed Ph+ CML. If cobicistat is discontinued, a washout period should be allowed before adjusting the nilotinib dosage upward to the indicated dose. Nilotinib is a substrate and moderate inhibitor of CYP3A4 and cobicistat is a substrate and a strong inhibitor of CYP3A4.
    Nimodipine: (Major) Avoid coadministration of nimodipine with cobicistat due to the risk of significant hypotension. If concomitant use is unavoidable, monitor blood pressure and reduce the dose of nimodipine as clinically appropriate. Nimodipine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Nintedanib: (Moderate) Dual inhibitors of P-glycoprotein (P-gp) and CYP3A4, such as cobicistat, may increase the exposure and clinical effect of nintedanib. If use together is necessary, closely monitor for increased nintedanib side effects including gastrointestinal toxicity (nausea, vomiting, diarrhea, abdominal pain, loss of appetite), headache, elevated liver enzymes, and hypertension. A dose reduction, interruption of therapy, or discontinuation of nintedanib therapy may be necessary. Cobicistat is a mild inhibitor of both P-gp and CYP3A4; nintedanib is a P-gp substrate and a minor CYP3A4 substrate. In drug interactions studies, administration of nintedanib with a dual P-gp and CYP3A4 inhibitor increased nintedanib AUC by 60%.
    Nisoldipine: (Major) Avoid coadministration of nisoldipine with cobicistat due to increased plasma concentrations of nisoldipine. If coadministration is unavoidable, monitor blood pressure closely during concurrent use of these medications. Nisoldipine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Norethindrone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Norethindrone; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Norgestimate; Ethinyl Estradiol: (Major) Concurrent administration of cobicistat and norgestimate results in increased norgestimate serum concentrations. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is also the potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Norgestrel: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norgestrel. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Nortriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Octreotide: (Moderate) Caution is warranted when cobicistat is administered with octreotide as there is a potential for elevated concentrations of cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Octreotide inhibits CYP3A4; cobicistat is a CYP3A4 substrate.
    Olanzapine: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6.
    Olanzapine; Fluoxetine: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6. (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Olanzapine; Samidorphan: (Moderate) Caution is warranted when cobicistat is administered with olanzapine as there is a potential for elevated olanzapine concentrations. Olanzapine is a substrate of CYP2D6. Cobicistat is an inhibitor of CYP2D6.
    Olaparib: (Major) Avoid coadministration of olaparib with cobicistat due to the risk of increased olaparib-related adverse reactions. If concomitant use is unavoidable, reduce the dose of olaparib to 100 mg twice daily; the original dose may be resumed 3 to 5 elimination half-lives after cobicistat is discontinued. Olaparib is a CYP3A substrate and cobicistat is a strong CYP3A4 inhibitor; concomitant use may increase olaparib exposure. Coadministration with another strong CYP3A inhibitor increased the olaparib Cmax by 42% and the AUC by 170%.
    Oliceridine: (Moderate) Monitor patients closely for respiratory depression and sedation at frequent intervals and base subsequent doses on the patient's severity of pain and response to treatment if concomitant administration of oliceridine and cobicistat is necessary; less frequent dosing of oliceridine may be required. Concomitant use of oliceridine and cobicistat may increase the plasma concentration of oliceridine, resulting in increased or prolonged opioid effects. If cobicistat is discontinued, consider increasing the oliceridine dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oliceridine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Ombitasvir; Paritaprevir; Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4. (Moderate) Monitor for an increase in paritaprevir-related adverse reactions if coadministration with cobicistat is necessary. Paritaprevir is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased paritaprevir exposure by 2.2-fold to 2.9-fold.
    Omeprazole: (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
    Omeprazole; Amoxicillin; Rifabutin: (Major) Caution is recommended during coadministration of rifabutin with cobicistat. Concurrent use may result in elevated plasma concentrations of rifabutin. If these drugs are used together, the recommended dosage regimen for rifabutin is 150 mg every other day. Monitor for rifabutin-associated adverse reactions, such as neutropenia and uveitis. (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
    Omeprazole; Sodium Bicarbonate: (Minor) The plasma concentrations of omeprazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while omeprazole is a CYP3A4 substrate.
    Ondansetron: (Moderate) The plasma concentrations of ondansetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI or CNS effects, is recommended during coadministration. Cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-glycoprotein (P-gp) inhibitor. Ondansetron is a CYP3A4, CYP2D6, and P-gp substrate.
    Oritavancin: (Major) Plasma concentrations and efficacy of cobicistat and/or the drugs that are boosted by cobicistat may be reduced if these drugs are administered concurrently with oritavancin. Cobicistat is metabolized by CYP3A4 and CYP2D6; oritavancin is a weak CYP3A4 and CYP2D6 inducer. Cobicistat is a CYP3A4 inhibitor indicated to increase systemic exposure of other antiretrovirals.
    Osilodrostat: (Major) Reduce the dose of osilodrostat by one-half during coadministration of cobicistat; concurrent use may increase osilodrostat exposure and the risk of osilodrostat-related adverse reactions. Osilodrostat is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Ospemifene: (Moderate) Monitor for an increase in ospemifene-related adverse reactions if coadministration with cobicistat is necessary. Ospemifene is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Oxcarbazepine: (Major) Coadministration of oxcarbazepine with regimens containing cobicistat and atazanavir or darunavir should be avoided. If these drugs are used together, significant decreases in the plasma concentrations of cobicistat, atazanavir and potentally darunavir may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Oxybutynin: (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
    Oxycodone: (Moderate) Consider a reduced dose of oxycodone with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the oxycodone dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Oxycodone is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase oxycodone exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of oxycodone. If cobicistat is discontinued, oxycodone plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to oxycodone.
    Paclitaxel: (Moderate) Plasma concentrations of paclitaxel may be elevated when administered concurrently with cobicistat. Cobicistat is a strong inhibitor of CYP3A4 and P-glycoprotein (P-gp) inhibitor, while paclitaxel is a CYP3A4 and P-gp substrate. Some experts state that pharmacokinetic interactions between paclitaxel and some CYP3A4 inhibitors do not appear to be clinically significant. However, combining the drugs in clinical practice may require close monitoring to ensure proper therapeutic responses.
    Palbociclib: (Major) Avoid coadministration of cobicistat with palbociclib; significantly increased plasma exposure of palbociclib may occur. If concomitant use cannot be avoided, reduce the dose of palbociclib to 75 mg PO once daily and monitor for increased adverse reactions. If cobicistat is discontinued, increase the palbociclib dose (after 3 to 5 half-lives of cobicistat) to the dose used before initiation of cobicistat. Palbociclib is primarily metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. In a drug interaction trial, coadministration with another strong CYP3A4 inhibitor increased the AUC and Cmax of palbociclib by 87% and 34%, respectively.
    Palonosetron: (Moderate) The plasma concentrations of palonosetron may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is an inhibitor of CYP3A4 and CYP2D6; palonosetron is a substrate of both CYP3A4 and CYP2D6.
    Panobinostat: (Major) Reduce the starting dose of panobinostat to 10 mg when coadministered with cobicistat. Concurrent use may increase systemic exposure of panobinostat. Panobinostat is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the AUC of panobinostat by 73%.
    Paricalcitol: (Moderate) Monitor plasma PTH and serum calcium and phosphorous concentrations if a patient initiates or discontinues therapy with both paricalcitol and cobicistat, or during periods of dose titration. If hypercalcemia occurs, the dose of paricalcitol should be reduced or withheld until these parameters are normalized. cobicistat is a strong CYP3A4 inhibitor and paricalcitol is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor approximately doubled the exposure of paricalcitol.
    Paroxetine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Pazopanib: (Major) Avoid coadministration of pazopanib and cobicistat due to the potential for increased exposure of both pazopanib and cobicistat. If concurrent use is unavoidable, reduce the pazopanib dose to 400 mg PO once daily; further dose adjustments may be necessary if adverse effects occur. Pazopanib is an inhibitor and substrate of CYP3A4; cobicistat is a strong CYP3A4 inhibitor and a CYP3A4 substrate. Concurrent use of pazopanib another strong CYP3A4 inhibitor increased the Cmax and AUC of pazopanib by 1.5-fold and 1.7-fold, respectively. In addition, pazopanib is a substrate/inhibitor of P-glycoprotein (P-gp), an inhibitor of CYP2D6, and a substrate of breast cancer resistance protein (BCRP). Cobicistat is an inhibitor of P-gp, BCRP, and a substrate/inhibitor of CYP2D6.
    Pemigatinib: (Major) Avoid coadministration of pemigatinib and cobicistat due to the risk of increased pemigatinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of pemigatinib to 9 mg PO once daily if original dose was 13.5 mg per day and to 4.5 mg PO once daily if original dose was 9 mg per day. If cobicistat is discontinued, resume the original pemigatinib dose after 3 elimination half-lives of cobicistat. Pemigatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased pemigatinib exposure by 88%.
    Pentamidine: (Moderate) The plasma concentrations of pentamidine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as nephrotoxicity or electrolyte disorders, is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while pentamidine is a CYP2D6 substrate.
    Pentazocine; Naloxone: (Moderate) The plasma concentrations of buprenorphine and naloxone may be elevated when administered concurrently with cobicistat. When initiating buprenorphine; naloxone in patients currently on a regimen containing cobicistat and atazanavir or darunavir, use the lowest buprenorphine; naloxone starting dose and slowly titrate to desired effect. When initiating antiretroviral regimens containing cobicistat and atazanavir or darunavir to patients on buprenorphine; naloxone, an adjustment of buprenorphine; naloxone dose may be needed. Monitoring for adverse effects, such as CNS side effects or respiratory depression, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while buprenorphine is a CYP3A4 substrate.
    Perampanel: (Major) Caution is warranted when cobicistat is administered with perampanel as there is a potential for elevated perampanel concentrations and decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Perampanel is a substrate and inducer of CYP3A4. Cobicistat is a CYP3A4 substrate and inhibitor.
    Perindopril; Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Perphenazine: (Moderate) The plasma concentrations of perphenazine may be elevated when administered concurrently with cobicistat. During coadministration, a reduction in the perphenazine dose may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is an inhibitor of CYP2D6, an isoenzyme responsible for the metabolism of perphenazine. These drugs used in combination may result in elevated perphenazine plasma concentrations, causing an increased risk for perphenazine-related adverse events.
    Perphenazine; Amitriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations. (Moderate) The plasma concentrations of perphenazine may be elevated when administered concurrently with cobicistat. During coadministration, a reduction in the perphenazine dose may be required. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. Cobicistat is an inhibitor of CYP2D6, an isoenzyme responsible for the metabolism of perphenazine. These drugs used in combination may result in elevated perphenazine plasma concentrations, causing an increased risk for perphenazine-related adverse events.
    Pexidartinib: (Major) Avoid coadministration of pexidartinib with cobicistat as concurrent use may increase pexidartinib exposure. Concurrent use may also result in decreased plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. If concurrent use cannot be avoided, reduce the dose of pexidartinib as follows: 800 mg/day or 600 mg/day of pexidartinib, reduce to 200 mg twice daily; 400 mg/day of pexidartinib, reduce to 200 mg once daily. If cobicistat is discontinued, increase the pexidartinib dose to the original dose after 3 plasma half-lives of cobicistat. Pexidartinib is a CYP3A4 substrate and moderate CYP3A4 inducer; cobicistat is a CYP3A4 substrate and strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased pexidartinib exposure by 70%.
    Phenobarbital: (Contraindicated) Coadministration of phenobarbital with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Contraindicated) Coadministration of phenobarbital with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Phentermine; Topiramate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
    Phenytoin: (Contraindicated) Coadministration of phenytoin with cobicistat-containing regimens is contraindicated. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Pimavanserin: (Major) Reduce the dose of pimavanserin to 10 mg PO once daily and monitor for pimavanserin-related adverse reactions, including nausea, vomiting, confusion, loss of balance or coordination, and QT prolongation if coadministration with cobcistat is necessary. Concurrent use may increase pimavanserin exposure. Pimavanserin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. In drug interaction studies, coadministration with a strong CYP3A4 inhibitor increased exposure to pimavanserin by 3-fold.
    Pimozide: (Contraindicated) Coadministration of pimozide with cobicistat is contraindicated. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor; plasma concentrations of drugs extensively metabolized by these enzymes, such as pimozide, are expected to increase with concurrent use. Elevated plasma concentrations of pimozide have been associated with QT prolongation and serious cardiovascular adverse events including death due to torsade de pointes.
    Pioglitazone; Metformin: (Moderate) Concurrent administration of metformin and cobicistat may increase the risk of lactic acidosis. Cobicistat is a potent inhibitor of the human multidrug and toxic extrusion 1 (MATE1) on proximal renal tubular cells; metformin is a MATE1 substrate. Inhibition of MATE1 by cobicistat may decrease metformin eliminiation by blocking renal tubular secretion. If these drugs are given together, closely monitor for signs of metformin toxicity; metformin dose adjustments may be needed.
    Pirfenidone: (Moderate) Caution is warranted when cobicistat is administered with pirfenidone as there is a potential for elevated concentrations of both drugs. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is a substrate/inhibitor of CYP3A4 and CYP2D6. Pirfenidone is a substrate/inhibitor of CYP2D6 and a CYP3A4 inhibitor.
    Pitavastatin: (Major) The plasma concentrations of pitavastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or GI effects, is recommended during coadministration. Cobicistat is a organic anion transporting polypeptide (OATP) inhibitor, while pitavastatin is a OATP1B1 substrate.
    Polatuzumab Vedotin: (Moderate) Monitor for increased polatuzumab vedotin toxicity during coadministration of cobicistat due to the risk of elevated exposure to the cytotoxic component of polatuzumab vedotin, MMAE. MMAE is metabolized by CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Strong CYP3A4 inhibitors are predicted to increase the exposure of MMAE by 45%.
    Ponatinib: (Major) Avoid coadministration of ponatinib and cobicistat due to the potential for increased ponatinib exposure. If concurrent use cannot be avoided, reduce the ponatinib dose to the next lower dose level (45 mg to 30 mg; 30 mg to 15 mg; 15 mg to 10 mg). If the patient is taking ponatinib 10 mg once daily prior to concurrent use, avoid the use of cobicistat and consider alternative therapy. After cobicistat has been discontinued for 3 to 5 half-lives, resume the dose of ponatinib that was tolerated prior to starting cobicistat. Ponatinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the ponatinib AUC by 78%.
    Posaconazole: (Major) Caution is warranted when cobicistat is administered with posaconazole as there is a potential for elevated posaconazole and cobicistat concentrations. Posaconazole is a CYP3A4 inhibitor and a P-glycoprotein (P-gp) substrate. Cobicistat is an inhibitor of P-gp and a substrate of CYP3A4.
    Pralsetinib: (Major) Avoid coadministration of cobicistat with pralsetinib due to the risk of increased pralsetinib exposure which may increase the risk of adverse reactions. If concomitant use is unavoidable, reduce the dose of pralsetinib to 200 mg once daily for patients taking a daily dose of 400 mg or 300 mg, and to 100 mg once daily for patients taking a daily dose of 200 mg. After cobicistat has been discontinued for 3 to 5 elimination half-lives, resume the pralsetinib dose taken prior to initiating cobicistat. Pralsetinib is a CYP3A and P-glycoprotein (P-gp) substrate and cobicistat is a combined P-gp and strong CYP3A inhibitor. Coadministration with another combined P-gp and strong CYP3A inhibitor increased the AUC of pralsetinib by 251%.
    Pravastatin: (Major) The plasma concentrations of pravastatin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as rhabdomyolysis or GI effects, is recommended during coadministration. Cobicistat is a organic anion transporting polypeptide (OATP) inhibitor, while pravastatin is a OATP1B1 substrate.
    Prednisone: (Moderate) Coadministration of prednisone with cobicistat may cause elevated prednisone serum concentrations, potentially resulting in Cushing's syndrome and adrenal suppression. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor, while prednisone is a CYP3A4 and P-gp substrate. Corticosteroids, such as beclomethasone and prednisolone, whose concentrations are less affected by strong CYP3A4 inhibitors, should be considered, especially for long-term use.
    Primidone: (Contraindicated) Coadministration of primidone with cobicistat-containing regimens is contraindicated. Primidone is converted to phenobarbital, a CYP3A4 inducer, while cobicistat is a substrate of CYP3A4. If these drugs are used together, significant decreases in the plasma concentrations of the antiretrovirals may occur, resulting in reduction of antiretroviral efficacy and development of viral resistance. Consider use of an alternative anticonvulsant or antiretroviral therapy.
    Probenecid; Colchicine: (Major) Due to the risk for serious colchicine toxicity including multi-organ failure and death, avoid coadministration of colchicine and cobicistat in patients with normal renal and hepatic function unless the use of both agents is imperative. Coadministration is contraindicated in patients with renal or hepatic impairment because colchicine accumulation may be greater in these populations. Cobicistat can inhibit colchicine's metabolism via P-glycoprotein (P-gp) and CYP3A4, resulting in increased colchicine exposure. If coadministration in patients with normal renal and hepatic function cannot be avoided, adjust the dose of colchicine by either reducing the daily dose or the dosage frequency, and carefully monitor for colchicine toxicity. Specific dosage adjustment recommendations are available for the Colcrys product for patients who have taken a P-gp/strong CYP3A4 inhibitor like cobicistat in the past 14 days or require concurrent use: for prophylaxis of gout flares, if the original dose is 0.6 mg twice daily, decrease to 0.3 mg once daily or if the original dose is 0.6 mg once daily, decrease to 0.3 mg once every other day; for treatment of gout flares, give 0.6 mg as a single dose, then 0.3 mg 1 hour later, and do not repeat for at least 3 days; for familial Mediterranean fever, do not exceed a 0.6 mg/day.
    Progesterone: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with progesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy. The metabolism of progesterone may also be inhibited by cobicistat, a strong inhibitor of the CYP3A4 hepatic enzyme. This interaction does not apply to vaginal preparations of progesterone (e.g., Crinone, Endometrin).
    Promethazine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
    Promethazine; Dextromethorphan: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6. (Moderate) Use of dextromethorphan with cobicistat may result in increased dextromethorphan exposure. Cobicistat inhibits CYP2D6 and dextromethorphan is a CYP2D6 substrate. Monitor for dextromethorphan-related side effects, such as drowsiness, nausea or vomiting, sweating, restlessness, or tremor.
    Promethazine; Phenylephrine: (Moderate) Caution is warranted when cobicistat is administered with promethazine as there is a potential for elevated promethazine and cobicistat concentrations. Promethazine is a CYP2D6 substrate/inhibitor and cobicistat is a substrate/inhibitor of CYP2D6.
    Propafenone: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of propafenone with cobicistat. Propafenone is a substrate for CYP3A4 and a substrate and inhibitor of CYP2D6; cobicistat is a substrate and inhibitor of both these enzymes. Concurrent use may result in elevated propafenone plasma concentration.
    Propranolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as propranolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
    Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as propranolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
    Protriptyline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Quazepam: (Moderate) The plasma concentrations of quazepam may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS depression, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while quazepam is a CYP3A4 substrate.
    Quetiapine: (Major) The plasma concentrations of quetiapine may be elevated when administered concurrently with cobicistat. The manufacturer of quetiapine recommends a quetiapine dose reduction to one-sixth the original dose during concurrent administration of CYP3A4 inhibitors, such as cobicistat. When cobicistat is discontinued, the dose should be increased by 6-fold.
    Quinidine: (Moderate) Caution and therapeutic drug concentrations monitoring, if available, is recommended during coadministration of quinidine with cobicistat. Quinidine is a substrate for CYP3A4 and P-glycoprotein (P-gp) and an inhibitor of CYP2D6 and P-gp; cobicistat is a substrate and inhibitor of both these enzymes and an inhibitor of P-gp. Concurrent use may result in elevated plasma concentration of both drugs.
    Quinine: (Moderate) Concurrent administration of cobicistat with quinine may elevate the concentrations of both drugs; thereby increasing the potential for adverse events. CYP3A4 is the major enzyme responsible for quinine metabolism. Other isoenzymes, including CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, have some role in the metabolism of quinine; however, the extent of involvement of each of these differs depending on methodology used in the studies. Quinine is also a substrate of P-glycoprotein (P-gp) drug transporter. Cobicistat is a strong inhibitor of CYP3A4, and an inhibitor of CYP2D6 and P-gp. Quinine may inhibit CYP3A4, while cobicistat is metabolized by CYP3A4.
    Rabeprazole: (Minor) Use caution when administering cobicistat and rabeprazole concurrently. Cobicistat is an inhibitor of CYP3A and rabeprazole is partially metabolized by CYP3A. Co-administration can theoretically increase rabeprazole exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Ramelteon: (Moderate) Monitor for an increase in ramelteon-related adverse reactions if coadministration with cobicistat is necessary. Ramelteon is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ramelteon exposure by 84%.
    Ranolazine: (Contraindicated) Concomitant use of ranolazine with cobicistat is contraindicated due to the potential for increased ranolazine plasma concentrations and therefore increased risk of QTc prolongation and possibly torsade de pointes. Ranolazine is a CYP3A4, CYP2D6, and P-glycoprotein (P-gp) substrate; cobicistat is a strong inhibitor of CYP3A4 and an inhibitor of CYP2D6 and P-gp. Coadministration of another strong CYP3A4 inhibitor increased plasma concentrations of ranolazine by 220%. Serum concentrations of cobicistat could also be increased as ranolazine is a CYP3A4 and CYP2D6 inhibitor, and cobicistat is a CYP3A4 and CYP2D6 substrate.
    Regorafenib: (Major) Avoid coadministration of regorafenib with cobicistat due to increased plasma concentrations of regorafenib and decreased plasma concentrations of the active metabolites M-2 and M-5, which may lead to increased toxicity. Regorafenib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased regorafenib exposure by 33% and decreased exposure of M-2 and M-5 by 93% each.
    Relugolix: (Major) Avoid concomitant use of relugolix and oral cobicistat. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer cobicistat at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor.
    Relugolix; Estradiol; Norethindrone acetate: (Major) Avoid concomitant use of relugolix and oral cobicistat. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer cobicistat at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-glycoprotein (P-gp) substrate and cobicistat is a P-gp inhibitor. (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with norethindrone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. It is not clear how cobicistat alters various progestin-only agents used for contraception, fertility or luteal support, or for hormone replacement therapy (HRT). Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When progestins are used for other purposes, monitor for altered clinical response to hormonal therapy.
    Repaglinide: (Moderate) Coadministration of repaglinide and cobicistat may increase plasma concentrations of repaglinide; if coadministration is necessary, repaglinide dosage adjustment may be required and an increased frequency of glucose monitoring is recommended. Cobicistat is a strong CYP3A4 inhibitor and an inhibitor of organic anion transporting polypeptide (OATP). Repaglinide is a CYP3A4 and OATP1B1 substrate. Coadministration with other strong CYP3A4 inhibitors increased repaglinide exposure by up to 1.5-fold.
    Retapamulin: (Moderate) Coadministration of retapamulin with strong CYP3A4 inhibitors, such as cobicistat, in patients younger than 24 months is not recommended. Systemic exposure of topically administered retapamulin may be higher in patients younger than 24 months than in patients 2 years and older. Retapamulin is a CYP3A4 substrate.
    Revefenacin: (Major) Coadministration of revefenacin is not recommended with cobicistat because it could lead to an increase in systemic exposure of the active metabolite of revefenacin and an increased potential for anticholinergic adverse effects. The active metabolite of revefenacin is a substrate of OATP1B1 and OATP1B3; cobicistat is an inhibitor of OATP1B1 and OATP1B3.
    Ribociclib: (Contraindicated) Coadministration of ribociclib with cobicistat is contraindicated, as elevated plasma concentrations of ribociclib may be associated with QT prolongation; exposure to cobicistat may also increase. Ribociclib is extensively metabolized by CYP3A4 and is a strong CYP3A4 inhibitor; cobicistat is a strong CYP3A4 inhibitor and CYP3A4 substrate. Coadministration of ribociclib with another strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers.
    Ribociclib; Letrozole: (Contraindicated) Coadministration of ribociclib with cobicistat is contraindicated, as elevated plasma concentrations of ribociclib may be associated with QT prolongation; exposure to cobicistat may also increase. Ribociclib is extensively metabolized by CYP3A4 and is a strong CYP3A4 inhibitor; cobicistat is a strong CYP3A4 inhibitor and CYP3A4 substrate. Coadministration of ribociclib with another strong inhibitor increased the ribociclib AUC and Cmax by 3.2-fold and 1.7-fold, respectively, in healthy volunteers.
    Rifabutin: (Major) Caution is recommended during coadministration of rifabutin with cobicistat. Concurrent use may result in elevated plasma concentrations of rifabutin. If these drugs are used together, the recommended dosage regimen for rifabutin is 150 mg every other day. Monitor for rifabutin-associated adverse reactions, such as neutropenia and uveitis.
    Rifampin: (Contraindicated) Coadministration of rifampin with cobicistat is contraindicated. Rifampin induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance.
    Rifapentine: (Major) Coadministration of cobicistat and rifapentine is not recommended as concurrent use may result in significant decreases in the plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and rifapentine is a strong CYP3A4 inducer.
    Rifaximin: (Moderate) Although the clinical significance of this interaction is unknown, concurrent use of rifaximin, a P-glycoprotein (P-gp) and organic anion-transporting polypeptide (OATP1A1/1B1/1B3) substrate, with cobicistat, a P-gp and OATP inhibitor, may substantially increase the systemic exposure to rifaximin; caution is advised if these drugs must be administered together. During one in vitro study, coadministration with cyclosporine, a potent P-gp and OATP inhibitor, resulted in an 83-fold and 124-fold increase in the mean Cmax and AUC of rifaximin, respectively. In patients with hepatic impairment, the effects of reduced metabolism and P-gp inhibition may further increase exposure to rifaximin.
    Rilpivirine: (Moderate) The plasma concentrations of rilpivirine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Rilpivirine is a CYP3A4 substrate and cobicistat is a strong inhibitor of CYP3A4.
    Rimegepant: (Major) Avoid coadministration of rimegepant with cobicistat; concurrent use may significantly increase rimegepant exposure. Rimegepant is a CYP3A4, P-gp, and BCRP substrate and cobicistat is a strong CYP3A4 inhibitor and P-gp and BCRP inhibitor. Coadministration of rimegepant with another strong CYP3A4 inhibitor increased rimegepant exposure by 4-fold.
    Ripretinib: (Moderate) Monitor patients more frequently for ripretinib-related adverse reactions if coadministered with cobicistat. Coadministration may increase the exposure of ripretinib and its active metabolite (DP-5439), which may increase the risk of adverse reactions. Ripretinib and DP-5439 are metabolized by CYP3A4 and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ripretinib and DP-5439 exposure by 99%.
    Risperidone: (Major) Coadministration of risperidone, a CYP2D6 substrate, and cobicistat, a potent CYP2D6 inhibitor, may increase plasma concentrations of risperidone. When oral risperidone is given with a potent CYP2D6 inhibitor, the dose of risperidone should not exceed 8 mg/day PO in adults. When initiating therapy, titrate risperidone slowly. Upon discontinuation of the CYP2D6 inhibitor, the risperidone dose should be re-evaluated and increased if necessary. For the long-acting risperidone injection, the current adult dosage should be closely monitored when a potent CYP2D6 inhibitor is initiated or discontinued. An adjustment of the dose may be required.
    Ritonavir: (Contraindicated) Use of ritonavir with cobicistat is not recommended, because of similar effects on CYP3A. Both ritonavir and cobicistat are potent inhibitors of CYP3A4.
    Rivaroxaban: (Major) Avoid concomitant administration of rivaroxaban and cobicistat; significant increases in rivaroxaban exposure may increase bleeding risk. Rivaroxaban is a substrate of CYP3A4/5 and the P-glycoprotein (P-gp) transporter. Cobicistat is a combined P-gp and strong CYP3A4 inhibitor. Concurrent use of a single dose of rivaroxaban and another combined P-gp and strong CYP3A4 inhibitor increased the steady-state rivaroxaban AUC and Cmax by 150% and 60%, respectively. Similar increases in pharmacodynamic effects such as factor Xa inhibition and PT prolongation were also observed.
    Roflumilast: (Moderate) Monitor for an increase in roflumilast-related adverse reactions if concomitant use with cobicistat is necessary. Concurrent use may increase roflumilast exposure. Roflumilast is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of roflumilast by 99%.
    Rolapitant: (Major) Use caution if cobicistat and rolapitant are used concurrently, and monitor for cobicistat-related adverse effects. Cobicistat is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant is expected to persist beyond 28 days for an unknown duration. Exposure to another CYP2D6 substrate, following a single dose of rolapitant increased about 3-fold on Days 8 and Day 22. The inhibition of CYP2D6 persisted on Day 28 with a 2.3-fold increase in the CYP2D6 substrate concentrations, the last time point measured.
    Romidepsin: (Moderate) Monitor for toxicity related to increased romidepsin exposure and follow the dose modifications for toxicity during initial administration of romidepsin with cobicistat. Romidepsin is a CYP3A4 and P-gp substrate; cobicistat is a P-gp inhibitor and strong CYP3A4 inhibitor. In a pharmacokinetic drug interaction trial a strong CYP3A4 inhibitor increased romidepsin AUC by approximately 25%.
    Ropivacaine: (Moderate) The plasma concentrations of ropivacaine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as hypotension, bradycardia or GI effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while ropivacaine is a CYP3A4 substrate.
    Rosuvastatin: (Major) Avoid concurrent administration of cobicistat and rosuvastatin. Taking these drugs together results in elevated rosuvastatin concentrations. If these drugs must be used together, use the lowest starting dose of rosuvastatin and carefully titrate while monitoring for adverse events (myopathy). Rosuvastatin is taken up into human hepatocytes mainly by organic anion transporting polypeptide (OATP)1B1 and OATP1B3. Cobicistat is an inhibitor of OATP.
    Rosuvastatin; Ezetimibe: (Major) Avoid concurrent administration of cobicistat and rosuvastatin. Taking these drugs together results in elevated rosuvastatin concentrations. If these drugs must be used together, use the lowest starting dose of rosuvastatin and carefully titrate while monitoring for adverse events (myopathy). Rosuvastatin is taken up into human hepatocytes mainly by organic anion transporting polypeptide (OATP)1B1 and OATP1B3. Cobicistat is an inhibitor of OATP.
    Ruxolitinib: (Major) Reduce the ruxolitinib dosage when coadministered with cobicistat in patients with myelofibrosis (MF) or polycythemia vera (PV) as increased ruxolitinib exposure and toxicity may occur. No dose adjustments are necessary for patients with graft-versus-host disease; however, monitor blood counts more frequently for toxicity and adjust ruxolitinib dosage for adverse reactions. In MF patients, reduce the initial dose to 10 mg PO twice daily for platelet count of 100,000 cells/mm3 or more and 5 mg PO once daily for platelet count of 50,000 to 99,999 cells/mm3. In PV patients, reduce the initial dose to 5 mg PO twice daily. In MF or PV patients stable on ruxolitinib dose of 10 mg PO twice daily or more, reduce dose by 50%; in patients stable on ruxolitinib dose of 5 mg PO twice daily, reduce ruxolitinib to 5 mg PO once daily. Avoid the use of cobicistat in MF or PV patients who are stable on a ruxolitinib dose of 5 mg PO once daily. Ruxolitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Sacubitril; Valsartan: (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Salmeterol: (Major) Concurrent use of salmeterol with cobicistat is not recommended due to the potential for increased cardiovascular adverse events, such as QT prolongation, palpitations, and sinus tachycardia. Coadministration may result in elevated salmeterol serum concentrations.
    Saquinavir: (Contraindicated) Use of saquinavir with cobicistat plus either atazanavir or darunavir is not recommended, as pharmacokinetic data are not available to provide appropriate dosage recommendations. Saquinavir is a substrate/inhibitor of CYP3A4 and P-glycoprotein (P-gp) substrate, cobicistat is a substrate/inhibitor of CYP3A4 as well as an inhibitor of P-gp, and atazanavir and daruanavir are CYP3A4 substrates.
    Saxagliptin: (Major) Limit the dose of saxagliptin to 2.5 mg PO once daily when administered with cobicistat due to significantly increased saxagliptin exposure. Saxagliptin is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of a strong CYP3A4 inhibitor with a single 100 mg dose of saxagliptin and a single 20 mg dose of saxagliptin increased the saxagliptin AUC by 2.45-fold and 3.67-fold, respectively.
    Segesterone Acetate; Ethinyl Estradiol: (Major) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with segesterone. Insufficient data are available to make dosage recommendations, particularly when cobicistat is combined in other antiviral regimens. Instruct women to report any breakthrough bleeding or other adverse effects (e.g., insulin resistance, dyslipidemia, and acne) to their prescribers. There is a potential for altered efficacy for combined hormonal contraceptives. Consider alternative methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. (Moderate) Consider the benefits and risk of administering antiretroviral regimens containing cobicistat with estrogens, such as ethinyl estradiol, or mestranol, which is converted to ethinyl estradiol. There is a potential for altered efficacy for combined hormonal contraceptives. Insufficient data are available to make dosage recommendations, particularly when cobicistat is used in combination regimens with other antiviral therapies. Consider alternative or additional methods of contraception, such as condoms, to prevent unwanted pregnancy and transmission of HIV/AIDS. When patients are taking estrogen for hormone replacement therapy (HRT), it may be prudent to monitor for reduced clinical efficacy or unusual vaginal bleeding patterns.
    Selective serotonin reuptake inhibitors: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Selpercatinib: (Major) Avoid coadministration of selpercatinib and cobicistat due to the risk of increased selpercatinib exposure which may increase the risk of adverse reactions, including QT prolongation. If coadministration is unavoidable, reduce the dose of selpercatinib to 40 mg PO twice daily if original dose was 120 mg twice daily, and to 80 mg PO twice daily if original dose was 160 mg twice daily. Monitor ECGs for QT prolongation more frequently. If cobicistat is discontinued, resume the original selpercatinib dose after 3 to 5 elimination half-lives of cobicistat. Selpercatinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selpercatinib exposure by 133%.
    Selumetinib: (Major) Avoid coadministration of selumetinib and cobicistat due to the risk of increased selumetinib exposure which may increase the risk of adverse reactions. If coadministration is unavoidable, reduce the dose of selumetinib to 20 mg/m2 PO twice daily if original dose was 25 mg/m2 twice daily and 15 mg/m2 PO twice daily if original dose was 20 mg/m2 twice daily. If cobicistat is discontinued, resume the original selumetinib dose after 3 elimination half-lives of cobicistat. Selumetinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased selumetinib exposure by 49%.
    Sertraline: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of selective serotonin reuptake inhibitors (SSRIs) and cobicistat. Concurrent use may result in elevated SSRI plasma concentrations. Predictions regarding this interaction can be made based on the metabolic pathways of these drugs. All SSRIs are substrates for the hepatic isoenzyme CYP2D6, while citalopram, escitalopram, and sertraline are also substrates for CYP3A4; cobicistat is an inhibitor of both CYP2D6 and CYP3A4.
    Sibutramine: (Moderate) The plasma concentrations of sibutramine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as serotonin syndrome or GI effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while sibutramine is a CYP3A4 substrate.
    Sildenafil: (Major) Sildenafil is contraindicated for use with cobicistat when used for pulmonary arterial hypertension (PAH). If used for erectile dysfunction, the dose of sildenafil should not exceed 25 mg in 48 hours with increased monitoring for adverse reactions during times of coadministration. Concurrent use is expected to substantially increase the sildenafil plasma concentrations and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Sildenafil is a sensitive CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the sildenafil AUC between 3- and 11-fold.
    Silodosin: (Contraindicated) Concurrent use of silodosin and cobicistat is contraindicated due to increased plasma concentrations of silodosin resulting in an increase of treatment-related adverse reactions. Cobicistat is a strong inhibitor of CYP3A4 and a P-glycoprotein (P-gp) inhibitor. Silodosin is a CYP3A4 and P-gp substrate. Coadministration with another strong CYP3A4 inhibitor increased silodosin exposure by 2.9-fold to 3.2-fold.
    Simeprevir: (Major) Avoid concurrent use of simeprevir and cobicistat. Inhibition of CYP3A4 by cobicistat may significantly increase the plasma concentrations of simeprevir, resulting in adverse effects. Coadministration with a moderate CYP3A4 inhibitor increased simeprevir exposure by 7.47-fold.
    Simvastatin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
    Simvastatin; Sitagliptin: (Contraindicated) Concomitant use of simvastatin with cobicistat is contraindicated due to increased simvastatin exposure and potential for myopathy, including rhabdomyolysis. Simvastatin is a substrate for CYP3A4; cobicistat is a strong CYP3A4 inhibitor.
    Siponimod: (Moderate) Concomitant use of siponimod and cobicistat may increase siponimod exposure. If the patient is also receiving a drug regimen containing a moderate CYP2C9 inhibitor, use of siponimod is not recommended due to a significant increase in siponimod exposure. Siponimod is a CYP2C9 and CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with a moderate CYP2C9/CYP3A4 dual inhibitor led to a 2-fold increase in the exposure of siponimod.
    Sirolimus: (Major) Avoid coadministration of sirolimus with cobicistat if possible due to increased plasma concentrations of sirolimus resulting in treatment-related adverse reactions. Sirolimus is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Sofosbuvir: (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP.
    Sofosbuvir; Velpatasvir: (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP. (Moderate) Monitor for velpatasvir-related adverse events when administering velpatasvir with cobicistat. In an interaction study, use of these drugs together resulted in a 50% increase in velpatasvir exposure; however, because data have not correlated velpatasvir exposure with toxicity, no dose adjustments are recommended. Velpatasvir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP1B1), Breast Cancer Resistance Protein (BCRP), and CYP3A; cobistat is an inhibitor of P-gp, OATP1B1, BCRP, and CYP3A4.
    Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) In an interaction study, use of cobicistat with sofosbuvir resulted in a 37% increase in sofosbuvir exposure; however, no dose adjustments are required. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). Sofosbuvir is a substrate of P-gp and BCRP. (Moderate) Monitor for velpatasvir-related adverse events when administering velpatasvir with cobicistat. In an interaction study, use of these drugs together resulted in a 50% increase in velpatasvir exposure; however, because data have not correlated velpatasvir exposure with toxicity, no dose adjustments are recommended. Velpatasvir is a substrate of P-glycoprotein (P-gp), organic anion transporting polypeptide (OATP1B1), Breast Cancer Resistance Protein (BCRP), and CYP3A; cobistat is an inhibitor of P-gp, OATP1B1, BCRP, and CYP3A4.
    Solifenacin: (Major) If coadministered with cobicistat, do not exceed a 5 mg daily dose of solifenacin in adults; do not exceed the initial starting dose in pediatric patients. The plasma concentrations of solifenacin may be elevated when administered concurrently with cobicistat. Monitor for excessive anticholinergic effects. Solifenacin is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased solifenacin exposure by 2.7-fold.
    Sonidegib: (Major) Avoid concomitant use of sonidegib and cobicistat as increased sonidegib plasma are expected, resulting in an increased risk of adverse events, particularly musculoskeletal toxicity. Cobicistat is a strong CYP3A4 inhibitor and may significantly increase the level of the CYP3A4 substrate, sonidegib. Coadministration of another strong CYP3A4 inhibitor increased the mean Cmax and AUC of sonidegib by 2.2-fold and 1.5-fold, respectively.
    Sotorasib: (Moderate) Coadministration of cobicistat with sotorasib may result in decreased plasma concentrations of cobicistat, leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. Cobicistat is a CYP3A4 substrate and sotorasib is a moderate CYP3A4 inducer.
    St. John's Wort, Hypericum perforatum: (Contraindicated) Coadministration of St. John's Wort, Hypericum perforatum with cobicistat is contraindicated. St. John's Wort induces CYP3A4; cobicistat is a substrate of this enzyme. Concurrent use may result in significant decreases in the plasma concentrations of cobicistat and of the simultaneously administered protease inhibitors (atazanavir or darunavir), leading to a reduction of antiretroviral efficacy and the potential development of viral resistance. St. John's Wort in all forms, including teas, should be avoided.
    Streptogramins: (Moderate) Caution is warranted when cobicistat is administered with dalfopristin; quinupristin as there is a potential for elevated cobicistat concentrations. Quinupristin is a CYP3A4 inhibitor and cobicistat is substrate of CYP3A4.
    Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if cobicistat must be administered. Consider a reduced dose of sufentanil injection with frequent monitoring for respiratory depression and sedation if concurrent use of cobicistat is necessary. If cobicistat is discontinued, consider increasing the sufentanil injection dose until stable drug effects are achieved and monitor for evidence of opioid withdrawal. Sufentanil is a CYP3A4 substrate, and coadministration with a strong CYP3A4 inhibitor like cobicistat can increase sufentanil exposure resulting in increased or prolonged opioid effects including fatal respiratory depression, particularly when an inhibitor is added to a stable dose of sufentanil. If cobicistat is discontinued, sufentanil plasma concentrations will decrease resulting in reduced efficacy of the opioid and potential withdrawal syndrome in a patient who has developed physical dependence to sufentanil.
    Sunitinib: (Major) Avoid coadministration of cobicistat with sunitinib if possible due to increased sunitinib exposure, which may increase the risk of QT prolongation. If concomitant use is unavoidable, monitor the QT interval more frequently and consider reducing the daily dose of sunitinib to a minimum of 37.5 mg for patients with GIST or RCC, and to a minimum of 25 mg for patients with pNET. Sunitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased exposure to sunitinib and its primary active metabolite by 51%.
    Suvorexant: (Major) Coadministration of suvorexant and cobicistat is not recommended due to the potential for significantly increased suvorexant exposure. Suvorexant is a CYP3A4 substrate. Cobicistat is a strong CYP3A4 inhibitor. Coadministration of another strong CYP3A4 inhibitor increased the suvorexant AUC by 2.8-fold.
    Tacrolimus: (Major) Decrease tacrolimus dose and closely monitor tacrolimus serum concentrations if coadministration with cobicistat is necessary; additional dosage reductions may be required. Concurrent use may increase tacrolimus serum concentrations and increase the risk of toxicity. Tacrolimus is a sensitive CYP3A4 substrate with a narrow therapeutic range; cobicistat is a strong CYP3A4 inhibitor.
    Tadalafil: (Major) Coadministration of tadalafil with cobicistat is expected to substantially increase the plasma concentrations of tadalafil and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. When used for pulmonary arterial hypertension (PAH) and the patient has been receiving cobicistat for at least 1 week, start tadalafil at 20 mg/day with an increase to 40 mg/day if tolerated. Avoid tadalafil during the initiation of cobicistat; it is recommended to stop tadalafil at least 24 hours prior to starting cobicistat. After the at least 1 week of cobicistat treatment, resume tadalafil at 20 mg daily with an increase to 40 mg daily based on tolerability. When used for erectile dysfunction, the manufacturer recommends a maximum tadalafil dose of 10 mg every 72 hours. It should be noted that during once daily administration of tadalafil, the presence of continuous plasma tadalafil concentrations may change the potential for interactions with potent inhibitors of CYP3A4
    Talazoparib: (Major) Avoid coadministration of cobicistat with talazoparib due to increased talazoparib exposure. If concomitant use is unavoidable, monitor for an increase in talazoparib-related adverse reactions. Talazoparib is a BCRP and P-glycoprotein (P-gp) substrate; cobicistat is a BCRP and P-gp inhibitor. Coadministration with other P-gp inhibitors increased talazoparib exposure by 8% to 45%. The effect of concomitant administration of BCRP inhibitors on the pharmacokinetics of talazoparib has not been studied; however, BCRP inhibitors may increase talazoparib exposure.
    Talimogene Laherparepvec: (Major) Consider the risks and benefits of treatment with talimogene laherparepvec before administering acyclovir or other antivirals to prevent or manage herpetic infection. Talimogene laherparepvec is a live, attenuated herpes simplex virus that is sensitive to acyclovir; coadministration with antiviral agents may cause a decrease in efficacy.
    Tamsulosin: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively.
    Tazemetostat: (Major) Avoid coadministration of tazemetostat with cobicistat as concurrent use may increase tazemetostat exposure and the frequency and severity of adverse reactions. Tazemetostat is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration of a moderate CYP3A4 inhibitor increased tazemetostat exposure by 3.1-fold.
    Telaprevir: (Major) Avoid concurrent use of cobicistat with telaprevir, as drug interaction data are not available. Clinically significant drug interactions may occur during coadministration.
    Telithromycin: (Major) Avoid concurrent use of telithromycin with regimens containing cobicistat and atazanavir or darunavir; use of an alternative antibiotic is recommended. Taking these drugs together may result in elevated concentations of telithromycin, cobicistat, atazanavir and darunavir. Both telithromycin and cobicistat are strong inhibitors of CYP3A4, an isoenzyme responsible for the metabolism of cobicistat, atazanavir and darunavir.
    Telmisartan; Amlodipine: (Moderate) Monitor for symptoms of hypotension and edema if coadministration of amlodipine with cobicistat is necessary; adjust the dose of amlodipine as clinically appropriate. Cobicistat is a strong CYP3A inhibitor and amlodipine is a CYP3A substrate. Coadministration with a moderate CYP3A4 inhibitor in elderly hypertensive patients increased systemic exposure to amlodipine by 60%. Strong CYP3A4 inhibitors may increase the plasma concentrations of amlodipine to a greater extent.
    Temsirolimus: (Major) Avoid coadministration of cobicistat with temsirolimus due to increased plasma concentrations of the primary active metabolite of temsirolimus (sirolimus). If concomitant use is unavoidable, consider reducing the dose of temsirolimus to 12.5 mg per week. Allow a washout period of approximately 1 week after discontinuation of cobicistat before increasing temsirolimus to its original dose. Temsirolimus is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor did not significantly affect temsirolimus exposure, but increased the AUC and Cmax of sirolimus by 3.1-fold and 2.2-fold, respectively.
    Teniposide: (Major) The plasma concentrations of teniposide may be significantly elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as myelosuppression, is recommended during coadministration. Cobicistat is a CYP3A4 and P-glycoprotein (P-gp) inhibitor, while teniposide is a CYP3A4 and P-gp substrate.
    Tenofovir Alafenamide: (Moderate) The plasma concentrations of tenofovir may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Cobicistat is an inhibitor of the drug transporters P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and organic anion transport protein (OATP1B1/1B3). Tenofovir alafenamide is a substrate for all three transporters.
    Tepotinib: (Major) Avoid concomitant use of tepotinib and cobicistat due to increased plasma concentrations of tepotinib, which may increase the incidence and severity of adverse reactions. Tepotinib is a CYP3A and P-gp substrate; cobicistat is a dual strong CYP3A and P-gp inhibitor.
    Terbinafine: (Moderate) Caution is advised when administering terbinafine with cobicistat. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may alter the systemic exposure of both drugs. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is an inhibitor of CYP2D6 and is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP3A4. Cobicistat is a substrate of CYP2D6 and an inhibitor of CYP3A4. Monitor patients for adverse reactions if these drugs are coadministered. Topical terbinafine formulations would not be expected to interact.
    Tetrabenazine: (Moderate) The plasma concentrations of tetrabenazine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is a CYP2D6 inhibitor, while tetrabenazine is a CYP2D6 substrate.
    Tezacaftor; Ivacaftor: (Major) If cobicistat and ivacaftor are taken together, administer ivacaftor at the usual recommended dose but reduce the frequency to twice weekly. Ivacaftor is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased ivacaftor exposure by 8.5-fold. (Major) Reduce the dosing frequency of tezacaftor; ivacaftor when coadministered with cobicistat; coadministration may increase tezacaftor; ivacaftor exposure and adverse reactions. When combined, dose 1 tezacaftor/ivacaftor combination tablet twice a week, approximately 3 to 4 days apart (i.e., Day 1 and Day 4). The evening dose of ivacaftor should not be taken. Both tezacaftor and ivacaftor are CYP3A substrates (ivacaftor is a sensitive substrate); cobicistat is a strong CYP3A inhibitor. Coadministration of a strong CYP3A inhibitor increased tezacaftor and ivacaftor exposure 4- and 15.6-fold, respectively.
    Theophylline, Aminophylline: (Moderate) Caution is warranted when cobicistat is administered with theophylline; aminophylline as there is a potential for elevated theophylline concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Theophylline is a substrate of CYP3A4; cobicistat is a CYP3A4 inhibitor.
    Thioridazine: (Contraindicated) Cobicistat is a mild inhibitor of CYP2D6 and the use of thioridazine concomitantly with CYP2D6 inhibitors is contraindicated due to the possible risk of QT prolongation and subsequent arrhythmias, or other serious side effects, occurring from elevated serum concentrations of thioridazine.
    Thiotepa: (Major) Avoid the concomitant use of thiotepa and cobicistat if possible; reduced metabolism to the active thiotepa metabolite may result in decreased thiotepa efficacy. Consider an alternative agent with no or minimal potential to inhibit CYP3A4. If coadministration is necessary, monitor patients for signs of reduced thiotepa efficacy. In vitro, thiotepa is metabolized via CYP3A4 to the active metabolite, TEPA; cobicistat is a strong CYP3A4 inhibitor.
    Tiagabine: (Moderate) The plasma concentrations of tiagabine may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while tiagabine is a CYP3A4 substrate.
    Ticagrelor: (Major) Avoid coadministration of ticagrelor with cobicistat due to increased plasma concentrations of ticagrelor resulting in an increased risk of dyspnea, bleeding, and other treatment-related adverse reactions. Ticagrelor is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased ticagrelor exposure by 7.32-fold.
    Timolol: (Moderate) Coadministration of cobicistat (a CYP2D6 inhibitor) with beta-blockers metabolized by CYP2D6, such as timolol, may result in elevated beta-blocker serum concentrations. If used concurrently, close clinical monitoring with appropriate beta-blocker dose reductions are advised.
    Tinidazole: (Moderate) The plasma concentrations of tinidazole may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as GI effects, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while tinidazole is a CYP3A4 substrate.
    Tipranavir: (Contraindicated) Use of tipranavir with cobicistat plus either atazanavir or darunavir is not recommended, as pharmacokinetic data are not available to provide appropriate dosage recommendations. Use of tipranavir with either atazanavir; cobicistat or darunavir; cobicistat may lead to loss of antiretroviral efficacy and development of resistance. Tipranavir is a substrate/inhibitor of CYP3A4, an inhibitor of CYP2D6, and a substrate of P-glycoprotein (P-gp). Cobicistat is a substrate/inhibitor of both CYP2D6 and CYP3A4 as well as an inhibitor of P-gp, and atazanavir and daruanavir are CYP3A4 substrates.
    Tisotumab Vedotin: (Moderate) Monitor for tisotumab vedotin-related adverse reactions if concomitant use with cobicistat is necessary due to increased monomethyl auristatin E (MMAE) exposure which may increase the incidence and severity of adverse reactions. MMAE, the active component of tisotumab vedotin, is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Clinical drug interaction studies have not been conducted for tisotumab vedotin. However, coadministration of another antibody-drug conjugate that contains MMAE with a strong CYP3A inhibitor increased unconjugated MMAE exposure by 34%.
    Tofacitinib: (Major) A dosage reduction of tofacitinib is necessary if coadministered with cobicistat. In patients receiving 5 mg or less twice daily, reduce to once daily dosing; in patients receiving 10 mg twice daily, reduce to 5 mg twice daily; in patients receiving 22 mg once daily of the extended-release (XR) formulation, switch to 11 mg XR once daily; in patients receiving 11 mg XR once daily, switch to the immediate-release formulation at a dose of 5 mg once daily. Tofacitinib exposure is increased when coadministered with cobicistat. Cobicistat is a strong CYP3A4 inhibitor; tofacitinib is a CYP3A4 substrate. Coadministration with another strong CYP3A4 inhibitor increased tofacitinib exposure by 2-fold.
    Tolterodine: (Major) Reduce the dose of immediate-release tolterodine to 1 mg twice daily and extended-release tolterodine to 2 mg once daily if coadministered with cobicistat. Concurrent use may increase tolterodine exposure. Cobicistat is a strong CYP3A4 inhibitor. In CYP2D6 poor metabolizers, the CYP3A4 pathway becomes important in tolterodine elimination. Because it is difficult to assess which patients will be poor CYP2D6 metabolizers, reduced doses of tolterodine are advised when administered with strong CYP3A4 inhibitors. In a drug interaction study, coadministration of a strong CYP3A4 inhibitor increased the tolterodine AUC by 2.5-fold in CYP2D6 poor metabolizers.
    Tolvaptan: (Contraindicated) The concomitant use of tolvaptan and cobicistat is contraindicated. Concurrent use is expected to increase tolvaptan exposure. Tolvaptan is a sensitive CYP3A4 substrate; cobicistat is a strong inhibitor of CYP3A4. Coadministration of another strong CYP3A4 inhibitor increased tolvaptan exposure 5-fold. No data exists regarding the appropriate dose adjustment needed to allow safe administration of tolvaptan with strong CYP3A4 inhibitors.
    Topiramate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
    Topotecan: (Major) Avoid coadministration of cobicistat with oral topotecan due to increased topotecan exposure; cobicistat may be administered with intravenous topotecan. Oral topotecan is a substrate of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP); cobicistat is a P-gp and BCRP inhibitor. Following escalating doses of a dual inhibitor of BCRP and P-gp, the AUC of topotecan lactone and total topotecan increased by approximately 2.5-fold compared to topotecan alone. Coadministration of a dual P-gp/BCRP inhibitor with intravenous topotecan increased total topotecan exposure by 1.2-fold and exposure to topotecan lactone by 1.1-fold.
    Toremifene: (Major) Avoid coadministration of cobicistat with toremifene if possible due to increased plasma concentrations of toremifene which may result in QT prolongation. If concomitant use is unavoidable, closely monitor ECGs for QT prolongation and monitor electrolytes; correct hypokalemia or hypomagnesemia prior to administration of toremifene. Toremifene is a CYP3A4 substrate that has been shown to prolong the QTc interval in a dose- and concentration-related manner, and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased toremifene exposure by 2.9-fold; exposure to N-demethyltoremifene was reduced by 20%.
    Trabectedin: (Major) Avoid the concomitant use of trabectedin with cobicistat due to the risk of increased trabectedin exposure. Trabectedin is a CYP3A substrate and cobicistat is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased the systemic exposure of a single dose of trabectedin (0.58 mg/m2 IV) by 66% compared to a single dose of trabectedin (1.3 mg/m2) given alone.
    Tramadol: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Tramadol; Acetaminophen: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Trandolapril; Verapamil: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as verapamil, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate dose reductions are advised.
    Trazodone: (Major) Avoid coadministration of trazodone with cobicistat due to the potential for increased trazodone exposure and associated adverse effects including QT prolongation. If concurrent use cannot be avoided, consider a reduced dose of trazodone based on tolerability. Trazodone is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration of other strong CYP3A4 inhibitors increased the exposure of trazodone compared to the use of trazodone alone.
    Triamcinolone: (Moderate) Cobicistat may inhibit the CYP3A4 metabolism of triamcinolone, resulting in increased plasma triamcinolone concentrations and reduced serum cortisol concentrations. There have been reports of clinically significant drug interactions in patients receiving another strong CYP3A4 inhibitor with triamcinolone, resulting in systemic corticosteroid effects including, but not limited to, Cushing syndrome and adrenal suppression. Consider the benefit-risk of concomitant use and monitor for systemic corticosteroid side effects. Consider using an alternative treatment to triamcinolone, such as a corticosteroid not metabolized by CYP3A4 (i.e., beclomethasone or prednisolone). In some patients, a corticosteroid dose adjustment may be needed. If corticosteroid therapy is to be discontinued, consider tapering the dose over a period of time to decrease the potential for withdrawal.
    Triazolam: (Contraindicated) Coadministration of triazolam, a primary CYP3A4 substrate, with strong CYP3A4 inhibitors, such as cobicistat, is contraindicated by the manufacturer of triazolam due to the risk for increased and prolonged sedation and respiratory depression. Concurrent use is expected to produce large increases in systemic exposure to triazolam, with the potential for serious adverse effects.
    Tricyclic antidepressants: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Trimipramine: (Moderate) Close monitoring for antidepressant response and careful dose titrations of the antidepressant therapy is recommended during coadministration of tricyclic antidepressants (TCAs) and cobicistat. Concurrent use may result in elevated TCA plasma concentrations.
    Tucatinib: (Moderate) Monitor for cobicistat-related adverse effects if coadministered with tucatinib as concurrent use may increase cobicistat exposure. Cobicistat is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor.
    Ubrogepant: (Contraindicated) Coadministration of ubrogepant and cobicistat is contraindicated as concurrent use may increase ubrogepant exposure and the risk of adverse effects. Ubrogepant is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor resulted in a 9.7-fold increase in the exposure of ubrogepant.
    Ulipristal: (Moderate) Use of ulipristal and cobicistat may increase the plasma concentration of ulipristal but is not likely to be significant for single-dose emergency contraceptive use. Avoid cobicistat if ulipristal is given chronically for hormonal conditions. Concomitant use of ulipristal, a CYP3A4 substrate, and cobicistat, a strong CYP3A4 inhibitor, may increase the plasma concentration of ulipristal resulting in an increased risk for ulipristal-related adverse events. Coadministration with another strong CYP3A4 inhibitor increased ulipristal exposure by 5.9-fold and increased the AUC of monodemethyl-ulipristal acetate by 2.4-fold.
    Umeclidinium; Vilanterol: (Moderate) Caution is warranted when cobicistat is administered with umeclidinium; vilanterol as there is a potential for elevated umeclidinium; vilanterol concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Umeclidinium; vilanterol is a substrate of CYP3A4, CYP2D6, and P-glycoprotein (P-gp). Cobicistat is an inhibitor of CYP3A4, CYP2D6, and P-gp inhibitor.
    Upadacitinib: (Moderate) Use upadacitinib with caution in patients receiving chronic treatment with cobicistat as upadacitinib exposure and adverse effects may be increased. Upadacitinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Concurrent use of upadacitinib with a strong inhibitor increased upadacitinib exposure by 75%.
    Valbenazine: (Major) Reduce the dose of valbenazine to 40 mg once daily if coadministration with cobicistat is necessary. Prolongation of the QT interval is not clinically significant at valbenazine concentrations expected with recommended dosing; however, valbenazine concentrations may be higher in patients taking a strong CYP3A4 inhibitor, and QT prolongation may become clinically significant. Valbenazine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased both valbenazine and NBI-98782 exposure by approximately 2-fold.
    Valproic Acid, Divalproex Sodium: (Major) Caution is warranted when cobicistat is administered with valproic acid as there is a potential for altered concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Valproic acid is a weak inhibitor and inducer (in vitro) of CYP3A4; cobicistat is a CYP3A4 substrate.
    Valsartan: (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Valsartan; Hydrochlorothiazide, HCTZ: (Minor) Caution is warranted when cobicistat is administered with valsartan as there is a potential for increased valsartan concentrations. Valsartan is a substrate of organic anion transporting polypeptide (OATP)1B1. Cobicistat is an inhibitor of OATP.
    Vardenafil: (Major) Do not use vardenafil orally disintegrating tablets with cobicistat due to increased vardenafil exposure; do not exceed a single dose of 2.5 mg per 72-hour period of vardenafil oral tablets. Vardenafil is primarily metabolized by CYP3A4/5; cobicistat is a strong CYP3A4 inhibitor. Coadministration with other strong CYP3A4 inhibitors increased the AUC of vardenafil by 10 to 16-fold.
    Vemurafenib: (Major) Avoid the concomitant use of vemurafenib and cobicistat; vemurafenib exposure may be increased resulting in an increased risk of adverse events, including QT prolongation. If use with cobicistat cannot be avoided, consider a vemurafenib dose reduction; monitor patients closely for the development of adverse events and dose reduce or discontinue therapy based on manufacturer guidance. Vemurafenib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased the exposure of vemurafenib by 40%.
    Venetoclax: (Major) Coadministration of cobicistat with venetoclax is contraindicated during the initiation and ramp-up phase in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL); consider an alternative medication or adjust the venetoclax dose with close monitoring for toxicity (e.g., hematologic toxicity, GI toxicity, and tumor lysis syndrome) in patients receiving a steady daily dose of venetoclax if concurrent use is necessary. In patients with acute myeloid leukemia (AML), reduce the venetoclax dose and monitor for toxicity during concurrent use. Resume the original venetoclax dose 2 to 3 days after discontinuation of cobicistat. Specific venetoclax dosage adjustments are as follows: CLL/SLL patients at steady daily dose: 100 mg/day. AML patients: 10 mg on day 1, 20 mg on day 2, 50 mg on day 3, then 100 mg/day starting on day 4. Venetoclax is a CYP3A4 and P-glycoprotein (P-gp) substrate; cobicistat is a CYP3A4 (strong) and P-gp inhibitor Coadministration of strong CYP3A4 inhibitors increased the venetoclax AUC by 90% to 690% in drug interaction studies, while coadministration with a single dose of another P-gp inhibitor increased venetoclax exposure by 78% in a drug interaction study.
    Venlafaxine: (Moderate) Monitor for adverse effects when administering venlafaxine with cobicistat. There is a potential for elevated venlafaxine and cobicistat concentrations if these drugs are given together. Venlafaxine and cobicistat are substrates and inhibitors of CYP2D6. In addition, venlafaxine is a substrate for CYP3A4; cobicistat is a strong inhibitor of CYP3A4.
    Verapamil: (Moderate) Coadministration of cobicistat (a strong CYP3A4 inhibitor) with calcium-channel blockers metabolized by CYP3A4, such as verapamil, may result in elevated calcium-channel blockers serum concentrations. If used concurrently, close clinical monitoring with appropriate dose reductions are advised.
    Vilazodone: (Major) Do not exceed a vilazodone dose of 20 mg once daily if coadministration with cobicistat is necessary; the original dose of vilazodone can be resumed if cobicistat is discontinued. Vilazodone is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased vilazodone exposure by 50%.
    Vinblastine: (Moderate) Monitor for an earlier onset and/or increased severity of vinblastine-related adverse reactions, including myelosuppression, constipation, and peripheral neuropathy, if coadministration with cobicistat is necessary. Vinblastine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Vincristine Liposomal: (Major) Avoid coadministration of vincristine with cobicistat due to increased plasma concentrations of vincristine, resulting in an earlier onset and/or increased severity of neuromuscular side effects. Vincristine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Vincristine: (Major) Avoid coadministration of vincristine with cobicistat due to increased plasma concentrations of vincristine, resulting in an earlier onset and/or increased severity of neuromuscular side effects. Vincristine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Vinorelbine: (Moderate) Monitor for an earlier onset and/or increased severity of vinorelbine-related adverse reactions, including constipation and peripheral neuropathy, if coadministration with cobicistat is necessary. Vinorelbine is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor.
    Voclosporin: (Contraindicated) Concomitant use of voclosporin and cobicistat is contraindicated; concomitant use may increase the exposure of voclosporin and the risk of voclosporin-related adverse effects such as nephrotoxicity, hypertension, and QT prolongation. Voclosporin is a sensitive CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased voclosporin exposure by approximately 19-fold.
    Vorapaxar: (Major) Avoid coadministration of vorapaxar with cobicistat due to increased plasma concentrations of vorapaxar and the risk of treatment-related adverse reactions. Vorapaxar is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased vorapaxar exposure by 2-fold; the bleeding risk for a change in exposure of this magnitude is not known.
    Voriconazole: (Major) Avoid concurrent use of voriconazole with regimens containing cobicistat and atazanavir or darunavir. Use of these drugs together may result in increase plasma concentrations of cobicistat, atazanavir, and darunavir; effects on the voriconazole concentrations has not been determined.
    Voxelotor: (Major) Avoid coadministration of voxelotor and cobicistat as concurrent use may increase voxelotor exposure and lead to increased toxicity. If coadministration is unavoidable, reduce voxelotor dosage to 1,000 mg PO once daily. Voxelotor is a substrate of CYP3A4; cobicistat is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor is predicted to increase voxelotor exposure by 42% to 83%.
    Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with cobicistat is necessary as concurrent use may increase the exposure of warfarin leading to increased bleeding risk. Cobicistat is a strong CYP3A4 inhibitor and the R-enantiomer of warfarin is a CYP3A4 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.
    Yohimbine: (Moderate) Caution is warranted when cobicistat is administered with yohimbine as there is a potential for elevated yohimbine concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Yohimbine is a substrate of CYP3A4 and CYP2D6; cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor.
    Zafirlukast: (Moderate) Caution is warranted when cobicistat is administered with zafirlukast as there is a potential for elevated concentrations of cobicistat. Clinical monitoring for adverse effects is recommended during coadministration. Zafirlukast inhibits CYP3A4; cobicistat is a CYP3A4 substrate.
    Zaleplon: (Moderate) Zaleplon is partially metabolized by CYP3A4, and concurrent use of strong CYP3A4 inhibitors, such as cobicistat, may decrease the clearance of zaleplon. Coadministration with a moderate CYP3A4 inhibitor increased zaleplon exposure by 20%. Routine dosage adjustments of zaleplon are not required. Dosage adjustments should be made on an individual basis according to efficacy and tolerability.
    Zanubrutinib: (Major) Decrease the zanubrutinib dose to 80 mg PO once daily if coadministered with cobicistat. Coadministration may result in increased zanubrutinib exposure and toxicity (e.g., infection, bleeding, and atrial arrhythmias). Interrupt zanubrutinib therapy as recommended for adverse reactions. After discontinuation of cobicistat, resume the previous dose of zanubrutinib. Zanubrutinib is a CYP3A4 substrate; cobicistat is a strong CYP3A4 inhibitor. The AUC of zanubrutinib was increased by 278% when coadministered with another strong CYP3A4 inhibitor.
    Zileuton: (Moderate) Caution is warranted when cobicistat is administered with zileuton as there is a potential for elevated zileuton concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Zileuton is a substrate of CYP3A4; cobicistat is a CYP3A4 inhibitor.
    Ziprasidone: (Moderate) The plasma concentrations of ziprasidone may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as extrapyramidal symptoms and CNS effects, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while ziprasidone is a CYP3A4 substrate.
    Zolmitriptan: (Moderate) Caution is warranted when cobicistat is administered with zolmitriptan as there is a potential for elevated zolmitriptan concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Zolmitriptan is a substrate of CYP3A4; cobicistat is a CYP3A4 inhibitor.
    Zolpidem: (Moderate) Consider decreasing the dose of zolpidem if coadministration with cobicistat is necessary. Zolpidem is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. Coadministration with strong CYP3A4 inhibitors increased the AUC of zolpidem by 34% to 70%.

    PREGNANCY AND LACTATION

    Pregnancy

    Antiretroviral therapy should be provided to all women during pregnancy, regardless of HIV RNA concentrations or CD4 cell count. Using highly active antiretroviral combination therapy (HAART) to maximally suppress viral replication is the most effective strategy to prevent the development of resistance and to minimize the risk of perinatal transmission. In treatment-naive women, begin HAART as soon as pregnancy is recognized or HIV is diagnosed, without waiting for the results of resistance testing; subsequent modifications to the treatment regimen should be made once the test results are available. Women who are currently receiving antiretroviral treatment when pregnancy is recognized should continue their treatment regimen if it is currently effective in suppressing viral replication; consider resistance testing if HIV RNA concentrations are more than 500 copies/mL. For women not currently receiving HAART, but who have previously received treatment, obtain a complete and accurate history of all prior antiretroviral regimens used and results of prior resistance testing, and perform resistance testing if HIV RNA concentrations are more than 500 copies/mL; treatment should be initiated prior to receiving resistance test results. Cobicistat-containing regimens are not recommended for use as initial therapies in pregnant women or women who are trying to conceive, as inadequate cobicistat concentrations and viral breakthroughs have been reported during the second and third trimesters. Consider the use of more effective antiretroviral regimens. If a cobicistat-containing regimen is used during pregnancy, frequently monitor viral loads (i.e., every 1 to 2 months). Data from the Antiretroviral Pregnancy Registry (APR), which includes more than 400 first trimester exposures to cobicistat, have shown no significant difference in the risk of overall major birth defects when compared to the 2.7% background rate among pregnant women in the US. When exposure occurred in the first trimester, the prevalence of defects was 3.9% (95% CI: 2.3 to 6.3). Regular laboratory monitoring is recommended to determine antiretroviral efficacy. Monitor CD4 counts at the initial visit. Women who have been on HAART for at least 2 years and have consistent viral suppression and CD4 counts consistently greater than 300 cells/mm3 do not need CD4 counts monitored after the initial visit during the pregnancy. However, CD4 counts should be monitored every 3 months during pregnancy for women on HAART less than 2 years, women with CD4 count less than 300 cells/mm3, or women with inconsistent adherence or detectable viral loads. Monitor plasma HIV RNA at the initial visit, 2 to 4 weeks after initiating or changing therapy, monthly until undetectable, then at least every 3 months, and at 34 to 36 weeks gestation. Perform antiretroviral resistance assay (genotypic testing, and if indicated, phenotypic testing) at baseline in all women with HIV RNA concentrations more than 500 copies/mL, unless they have already been tested for resistance. A first trimester ultrasound is recommended to confirm gestational age and provide an accurate estimation of gestational age at delivery. A second trimester ultrasound can be used for both anatomical survey and determination of gestational age in those patients not seen until later in gestation. Perform standard glucose screening in women receiving antiretroviral therapy at 24 to 28 weeks gestation, although it should be noted that some experts would perform earlier screening with ongoing chronic protease inhibitor-based therapy initiated prior to pregnancy, similar to recommendations for women with high-risk factors for glucose intolerance. Liver function testing is recommended within 2 to 4 weeks after initiating or changing antiretroviral therapy, and approximately every 3 months thereafter during pregnancy (or as needed). All pregnant women should be counseled about the importance of adherence to their antiretroviral regimen to reduce the potential for the development of resistance and perinatal transmission. It is strongly recommended that antiretroviral therapy, once initiated, not be discontinued. If a woman decides to discontinue therapy, a consultation with an HIV specialist is recommended. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to cobicistat; information about the registry can be obtained at www.apregistry.com or by calling 1-800-258-4263.[27468] [23512] [58000]

    To reduce the risk of postnatal transmission, mothers with HIV within the United States are advised by the Centers for Disease Control and Prevention to avoid breast-feeding. This recommendation applies to both untreated women and women who are receiving antiretroviral therapy, including regimens containing cobicistat. If a mother with HIV opts to breast-feed, the infant should undergo immediate diagnostic and virologic HIV testing. Testing should continue throughout breast-feeding and up to 6 months after cessation of breast-feeding. For expert consultation, health care workers may contact the Perinatal HIV Hotline (888-448-8765).[42452] It is unknown if cobicistat is present in human milk. Antiretroviral drugs whose passage into human breast milk have been evaluated include tenofovir, emtricitabine, nevirapine, zidovudine, lamivudine, and nelfinavir.

    MECHANISM OF ACTION

    Cobicistat is an inhibitor of CYP3A enzymes. It is used as a pharmacokinetic enhancer to increase the serum concentration of CYP3A substrates, such as the protease inhibitors atazanavir and darunavir. Cobicistat has no antiviral activity.

    PHARMACOKINETICS

    Cobicistat tablets are administered orally. After systemic absorption, the drug is extensively plasma protein bound (97% to 98%), with a mean blood to plasma ratio of 0.5. The majority of cobicistat metabolism is mediated by CYP3A enzymes with a minor amount of metabolism occurring via CYP2D6 enzymes. Cobicistat is eliminated via the feces (86.2%) and urine (8.2%), with a terminal plasma half-life of approximately 3 to 4 hours.
     
    Affected cytochrome P450 isoenzymes and drug transporters: CYP2D6, CYP3A4, P-gp, BCRP, MATE1, OATP1B1, and OATP1B3
    Cobicistat is a significant substrate of CYP3A, with a minor amount being metabolized by CYP2D6. Cobicistat also inhibits both CYP3A and CYP2D6, and is an inhibitor of the transporters P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), human multidrug and toxic extrusion 1 (MATE1), organic anion transporter polypeptide (OATP1B1), and OATP1B3. Concomitant administration with CYP3A4 inducers may lead to a loss of virologic efficacy and possible resistance. Coadministration with a potent CYP3A4 inhibitor (ketoconazole) does not require dosage adjustments.

    Oral Route

    Peak plasma concentration (Cmax) of cobicistat was observed 3.5 hours after oral administration. Pharmacokinetic studies were not conducted to determine if systemic exposure (AUC) was affected by the presence of food; however, because clinical trials were conducted under fed conditions, cobicistat should be administered with food.