Perinatal induction of hepatic aminopyrine N-demethylase by maternal exposure to phenytoin.

Phenytoin is one of the most commonly used anticonvulsants in pregnant epileptic women. Unrelatedly, the drug is also an inducer of hepatic drug metabolizing enzymes. We report here that maternal treatment with therapeutic-like doses for the rat of phenytoin produces significant elevations in the Michaelis constants and maximal velocities of hepatic aminopyrine N-demethylase in the dams' 8-day-old offspring. Although the drug apparently had little, if any, adverse effects on the course of pregnancy or neonatal development, it appears that the maternally administered phenytoin was transferred to the perinates where it induced hepatic drug metabolizing enzymes.