EFFECTS OF 23 DRUGS ON THE METABOLISM OF FK506 BY HUMAN LIVER-MICROSOMES

We investigated the effects of 23 drugs on the metabolism of FK506 by human liver microsomes. Acyclovir, amphotericin B, cefixime, cefotaxim e, ciprofloxacin, cyclosporin A, diltiazem, enoxacin, erythromycin, et hinyl estradiol, fluconazole, fosfomycin, kanamycin, lincomycin, loxop rofen, minocyclin, nifedipine, nilvadipine, norethindrone, ofloxacin, phenobarbital, prednisolone, or rifampicin was added to the reaction m edia at equimolar or at ten times an excess molar ratio of the substra te concentration; their effects on FK506 metabolism were examined. Dru gs known to be the substrate of cytochrome P-450 3A inhibited the meta bolism of FK506, and among the drugs tested, the inhibition by cyclosp orin A and nifedipine was the strongest.