Stribild is a combination tablet containing elvitegravir, emtricitabine, tenofovir disoproxil fumarate (TDF), and cobicistat.

Stribild has the potential to interact with many other drugs, mainly because of its cobicistat component. Cobicistat is a potent inhibitor of cytochrome P450 3A and 2D6 enzymes, and also inhibits the following transporters P-glycoprotein (P-gp), BCRP, OATP1B1, and OATP1B3, which can affect the absorption of other medications, increasing their concentration in the blood.

Common medications that may interact with Stribild include:

• Alfuzosin (potential for life-threatening low blood pressure)
• Antacids, such as aluminum and magnesium hydroxide. These may decrease the concentration of elvitegravir and administration should be separated by at least 2 hours
• Antiarrhythmics such as amiodarone, digoxin, disopyramide, flecainide, systemic lidocaine, mexiletine, propafenone, and quinidine (may increase blood levels of these drugs, therapeutic monitoring is required)
• Anticonvulsants such as carbamazepine, phenobarbital, phenytoin (do not administer together as reduces the effectiveness of elvitegravir). Some other anticonvulsants (such as oxcarbazepine) should also not be administered with Stribild and others (such as clonazepam or ethosuximide) may require increased monitoring
• Antidepressants, such as SSRIs (eg, paroxetine), TCADs (such as amitriptyline, nortriptyline), or trazodone
• Antifungals, such as itraconazole or ketoconazole (do not exceed 200mg/day of the antifungal); voriconazole should not be used unless the benefit far outweighs the risk
• Antipsychotics, such as lurasidone or pimozide (do not use together), quetiapine (reduce dosage to 1/6th), other antipsychotics (dosage reduction may be necessary)
• Benzodiazepines, such as diazepam, midazolam, triazolam (dosage reduction necessary)
• Beta-blockers, eg metoprolol, and timolol (dosage decrease may be necessary)
• Bosentan
• Calcium channel blockers, such as amlodipine or diltiazem (monitoring required)
• Cisapride (contraindicated)
• Clarithromycin (reduce the dosage of clarithromycin by 50% in people with CLCR between 50 mL/min and 60 mL/min)
• Colchicine (do not administer to people taking Stribild with kidney or liver disease; a lower dosage is necessary when treating gout flares in other Stribild patients)
• Corticosteroids, such as budesonide or dexamethasone, may decrease the effectiveness of elvitegravir. Consider alternatives such as prednisone that are less likely to affect CYP3A4
• Direct Oral Anticoagulants (DOACs), such as apixaban, betrixaban, dabigatran, edoxaban, and rivaroxaban (may increase the concentration of these medications, increasing bleeding risk)
• Drugs that induce CYP3A activity, such as dexamethasone, carbamazepine, phenytoin, phenobarbital, rifampin, rifabutin, and rifampicin (may lower blood concentrations of antiviral components which may lower the effectiveness of Stribild and increase the risk of resistance)
• Drugs that inhibit CYP3A, such as clarithromycin, erythromycin, diltiazem, itraconazole, ketoconazole, ritonavir, verapamil, goldenseal, and grapefruit (may decrease the clearance and increase the plasma concentration of cobicistat)
• Drugs that reduce kidney function or compete for renal excretion via active tubular secretion, such as acyclovir, ganciclovir, gentamicin, valacyclovir, valganciclovir, and high-dose or multiple NSAIDs
• Ergot derivatives such as dihydroergotamine, ergotamine (contraindicated)
• Hepatitis C antiviral agents (may increase the toxicity of tenofovir)
• Hormonal contraceptives such as those containing ethinylestradiol, levonorgestrel, or norgestimate (consider non-hormonal methods of contraception)
• Immunosuppressants such as cyclosporine, tacrolimus(may increase the concentration of the immunosuppressant)
• Lipid modifying agents such as atorvastatin or simvastatin (some are contraindicated, others require a dosage reduction)
• Narcotic analgesics, such as buprenorphine/naloxone, fentanyl, tramadol (may increase side effects of the narcotic; a dosage reduction may be required)
• PDE-5 inhibitors such as sildenafil, tadalafil, and vardenafil (may increase side effects of PDE-5 inhibitors and a dosage reduction is necessary)
• Salmeterol (the combination is not recommended)
• Warfarin (monitor carefully).