May inhibit metabolism & elevate serum levels of drugs metabolized by CYP3A isoenzyme eg, alprazolam, astemizole, carbamazepine, cilostazol, cisapride, cyclosporine, disopyramide, ergot alkaloids, lovastatin, methylprednisolone, midazolam, omeprazole, oral anticoagulants (eg, warfarin), pimozide, quinidine, rifabutin, sildenafil, simvastatin, tacrolimus, terfenadine, triazolam, & vinblastine; other CYP450 isoenzymes eg, phenytoin, theophylline, & valproate.