pentobarbital will lessen the extent or result of fesoterodine by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.pentobarbital will reduce the level or result of guanfacine by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Carefully. Solid or reasonable CYP3A4 inducers considerably reduce