Watch Intently (1)pentobarbital will lessen the extent or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Check Carefully. Coadministration of fentanyl with CYP3A4 inducers may lead to the decrease in fentanyl plasma concentrations, deficiency of efficacy or, potentially, improvement of the withdrawal syn… Read More