Induction of microsomal enzymes in rat liver by oxcarbazepine, 10,11-dihydro-10-hydroxy-carbamazepine and carbamazepine.

1. The effects of the new anti-epileptic drug, oxcarbazepine, its major metabolite in man, 10,11-dihydro-10-hydroxy-carbamazepine, and carbamazepine, on hepatic microsomal enzyme activities have been studied in rats after repeated administration of equimolar doses. 2. All three compounds caused a qualitatively similar induction of the mono-oxygenase system, the greatest increase being observed in the activity of 4-nitroanisole O-demethylase. Oxcarbazepine is as potent as carbamazepine, while 10,11-dihydro-10-hydroxy-carbamazepine is a weak inducer. 3. The observation that oxcarbazepine is a potent inducer in rats but not in man is explained by the species differences in its metabolism.