LIVER-ENZYME ACTIVITIES AFTER MULTIPLE ADMINISTRATION OF NIFEDIPINE IN MICE

The effect of multiple nifedipine administration on hexobarbital sleep ing time, liver monooxygenase and synthetase activities, lipid peroxid ation and microsomal membrane fluidity were studied in male albino mic e. The drug was administered orally at a dose of 25 mg/kg daily for 14 and 21 days. Nifedipine caused enzyme induction, demonstrated by shor tened hexobarbital sleeping time, enhanced ethylmorphine N-demethylase , aniline 4-hydroxylase, ethoxycoumarine O-deethylase, UDP-glucuronyl transferase, glutathione S-transferase and NADPH-cytochrome c reductas e activities and increased content of cytochrome P450 and cytochrome b (5). This effect persisted until the 7th day after the last dose of ni fedipine. There were no changes in lipid peroxidation and fluidity of the microsomal membranes after 14-day nifedipine administration. The i ncreased cytochrome P450 content and drug metabolizing enzyme activiti es could be not associated with changes in these liver microsomal memb rane properties.