pentobarbital will lower the level or outcome of fesoterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Check.pentobarbital decreases amounts of vandetanib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Steer clear of coadministration with strong CYP3A4 inducers; these drugs decrease exposure