Decreased plasma conc w/ CYP3A4 inducers eg, dexamethasone, phenytoin, carbamazepine, rifampicin, phenobarb, or
Hypericum perforatum (St. John's wort). Increased plasma conc w/ CYP3A4 inhibitors eg, ketoconazole, itraconazole, erythromycin, clarithromycin. May increase plasma conc of triazolobenzodiazepines, dihydropyridine Ca channel blockers, certain HMG-CoA reductase inhibitors ie, statins. Co-administration w/ CYP3A4 substrates w/ narrow therapeutic window eg, cyclosporine or pimozide. Inhibits CYP2C9 & CYP2C19. May prolong PT w/ warfarin.