Avoid concomitantly taking w/ anticoagulants (eg, warfarin), antiviral PIs (eg, saquinavir), anticancer agents (eg, busulfan, docetaxel, vinca alkaloids), Ca channel blockers (eg, dihydropyridines, verapamil), cyclosporin, tacrolimus, sirolimus, anti-epileptics (eg, phenytoin or carbamazepine), alfentanil, anxiolytics or tranquilizers (eg, buspirone, alprazolam, or brotizolam), midazolam IV, rifabutin, methylprednisolone, ebastine, reboxetine, sulphonylureas (eg, chlorpropamide, glibenclamide), sildenafil, trimetrexate.