When using any concomitant medication, the corresponding label should be consulted for information on the route of metabolism. Miconazole can inhibit the metabolism of drugs metabolised by the CYP3A4 and CYP2C9 enzyme systems. This can result in an increase and/or prolongation of their effects, including adverse effects.
Oral miconazole is contraindicated with the co-administration of drugs that are subject to metabolism by CYP3A4 (see Contraindications).
When co-administered with oral miconazole, the following drugs should be used with caution because of a possible increase or prolongation of the therapeutic outcome and/or adverse effects. If necessary, their dosage should be reduced, and where appropriate, plasma levels monitored: Drugs subject to metabolism by CYP2C9 (see Precautions): Oral anticoagulants eg, warfarin; oral hypoglycemics eg, sulfonylureas; phenytoin.
Other drugs subject to metabolism by CYP3A4: HIV protease inhibitors eg, saquinavir; certain antineoplastic agents eg, vinca alkaloids, busulfan and docetaxel; certain calcium-channel blockers eg, dihydropyridines and verapamil; certain immunosuppressive agents eg, cyclosporine, tacrolimus, sirolimus (rapamycin); others: Alfentanil, alprazolam, brotizolam, buspirone, carbamazepine, cilostasol, disopyramide, ebastine, methylprednisolone, midazolam IV, reboxetine, rifabutin, sildenafil and trimetrexate.