Viekira Pak

See Contraindications. Concomitant certain immunosuppressants or chemotherapeutic agents: may increase risk of HBV reactivation. Discontinue ethinyl estradiol-containing products prior to starting; may resume 2 weeks after therapy completion. May potentiate substrates of CYP3A, UGT1A1, BCRP, OATP1B1, or OATP1B3. Potentiated by strong CYP3A inhibitors or CYP2C8, P-gp, BCRP, OATP1B1, or OATP1B3 inhibitors. Potentiates ketoconazole (limit max 200mg/day), pravastatin (max 40mg/day), rosuvastatin (max 10mg/day), cyclosporine (reduce to ⅕ of current dose and monitor renal function), acetaminophen/hydrocodone (reduce dose by 50% and monitor). Potentiates ARBs (eg, valsartan, losartan, candesartan), CCBs (eg, amlodipine, nifedipine, diltiazem, verapamil); reduce dose of these (amlodipine by at least 50%) and monitor; consider alternatives if adverse effects occur. May potentiate anticancer agents/kinase inhibitors (eg, encorafenib, fostamatinib, ibrutinib, ivosidenib). Concomitant quetiapine: consider alternative anti-HCV therapy; if necessary, reduce quetiapine to ⅙ of current dose and monitor. Concomitant calcineurin inhibitors (in liver transplant): adjust dose of these. Concomitant fluticasone may reduce serum cortisol; consider alternatives. Concomitant voriconazole, darunavir/ritonavir, lopinavir/ritonavir, rilpivirine, salmeterol, metformin (in renal or hepatic impairment), elagolix 200mg twice daily (for >1 month): not recommended. Concomitant atazanavir 300mg (without ritonavir): give only in the AM. Antagonizes carisoprodol, cyclobenzaprine, diazepam; increase dose if needed. May antagonize omeprazole; consider increasing omeprazole dose: max 40mg/day. Caution with antiarrhythmics (eg, amiodarone, bepridil, disopyramide, flecainide, systemic lidocaine, mexiletine, propafenone, quinidine); monitor. Monitor with furosemide, buprenorphine/naloxone, alprazolam. Monitor INR frequently with warfarin.