pentobarbital will lessen the level or result of fentanyl transdermal by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Intently. Coadministration of fentanyl with CYP3A4 inducers may lead to a lessen in fentanyl plasma concentrations, not enough efficacy or, probably, development of a withdrawal syndrome inside a aff