Increased clearance w/ other medicinal products that induce microsomal enzymes; barbiturates, bosentan, carbamazepine, phenytoin, primidone, rifampicin, HIV medication (eg, ritonavir, nevirapine, efavirenz), & possibly felbamate, griseofulvin, oxcarbazepine, topiramate, St. John's Wort (
Hypericum perforatum). Increased or decreased plasma conc w/ HIV PIs (eg, ritonavir, nelfinavir), NNRTIs (eg, nevirapine, efavirenz) &/or combinations with HCV medicinal products (eg, boceprevir, telaprevir). Increased plasma conc w/ strong or moderate CYP3A4 inhibitors eg, azole antifungals (eg, fluconazole, itraconazole, ketoconazole, voriconazole), verapamil, macrolides (eg, clarithromycin, erythromycin), diltiazem & grapefruit juice. May increase plasma conc of cyclosporine. May decrease plasma conc of lamotrigine.