Increased plasma conc & adverse reactions w/ strong CYP3A inhibitors [eg, certain antivirals (boceprevir, cobicistat, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir), macrolide antibiotics (clarithromycin), antifungals (itraconazole, ketoconazole, posaconazole, voriconazole), conivaptan]; grapefruit or grapefruit juice. Decreased plasma conc & efficacy w/ strong CYP3A inducers (eg, rifampin, carbamazepine, phenytoin, St. John's Wort). Decreased conc & loss of efficacy of CYP3A substrates (eg, hormonal contraceptives).