pentobarbital will decrease the level or impact of diazepam by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.pentobarbital decreases levels of vandetanib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Prevent coadministration with powerful CYP3A4 inducers; these medicines lessen exposure to