May increase &/or prolong effects, including adverse effects of drugs metabolised by the CYP3A4 & CYP2C9 enzyme; may inhibit metabolism of CYP3A metabolized drugs eg, substrates known to prolong QT-interval eg, astemizole, bepridil, cisapride, dofetilide, halofantrine, mizolastine, pimozide, quinidine, sertindole & terfenadine; ergot alkaloids; HMG-CoA reductase inhibitors eg, simvastatin & lovastatin; triazolam & oral midazolam. Possible increase or prolongation of the therapeutic outcome &/or adverse effects eg, drugs metabolized by CYP2C9 eg, oral anticoagulants eg, warfarin; oral hypoglycemics eg, sulfonylureas; phenytoin); other drugs metabolized by CYP3A4 eg, HIV protease inhibitors eg, saquinavir; certain antineoplastic agents eg, vinca alkaloids, busulfan & docetaxel; certain Ca-channel blockers eg, dihydropyridines & verapamil; certain immunosuppressive agents eg, cyclosporine, tacrolimus, sirolimus (rapamycin). Alfentanil, alprazolam, brotizolam, buspirone, carbamazepine, cilostasol, disopyramide, ebastine, methylprednisolone, midazolam IV, reboxetine, rifabutin, sildenafil & trimetrexate.