PROTECTION FROM PHENYTOIN-INDUCED CONGENITAL-MALFORMATIONS BY COADMINISTRATION OF THE ANTIEPILEPTIC DRUG STIRIPENTOL IN A MOUSE MODEL

To test the hypothesis that the cytochrome P-450-inhibiting antiepileptic drug (AED) stiripentol (STP) can reduce the incidence of phenytoin (PI-IT) induced congenital malformations, we chronically administered the AEDs to three inbred mouse strains. The frequency of congenital defects in PHT-treated animals was dosage dependent, ranging from 7 to 55%. When STP was coadministered orally with PHT, there was a significant reduction in fetal defects in SWV and C57BL/6J mouse strains. A replication of the experiment was conducted with addition of a seventh group of mice that received the high dosage of PHT together with STP. In the replicate, all three strains demonstrated a significant reduction in fetal defects in fetuses exposed to PHT (60 mg/kg) and STP (200 mg/kg) as compared with PHT (60 mg/kg) monotherapy. These results strongly suggest that oxidative metabolites activated by cytochrome P-450 are the primary teratogenic molecules involved in PHT-induced teratogenesis and that clinical management of pregnant epileptic patients may be improved through heightened awareness of these drug interactions.