Increased clearance w/ hydantoin, barbiturates, primidone, carbamazepine, rifampicin. Increased liver enzyme induction w/ rifabutin, efavirenz, nevirapine, oxcarbazepine, topiramate, felbamate, ritonavir, nelfinavir, griseofulvin, St. John's wort containing-products. Reduced efficacy w/ ampicillin or tetracycline. Increased plasma & tissue conc of cyclosporin. Decreased plasma & tissue conc of lamotrigine. Increased risk of ALT elevations w/ ombitasvir/paritaprevir/ritonavir & dasabuvir w/ or w/o ribavirin. ACE inhibitors, angiontensin II receptor & aldosterone antagonists, K-sparing diuretics, NSAIDs.