Avoid terfenadine, astemizole, mizolastine, cisapride, triazolam, midazolam, dofetilide, quinidine, pimozide, simvastatin, lovastatin. Concomitant use w/ oral anticoagulants, saquinavir, vinca alkaloids, busulfan, docetaxel, dihydropyridines, verapamil, cyclosporine, tacrolimus, sirolimus, oral hypoglycaemics, phenytoin, carbamazepine, buspirone, alfentanil, sildenafil, alprazolam, brotizolam, rifabutin, methylprednisolone, trimetrexate, ebastine, reboxetine.