Observe Intently (one)pentobarbital will reduce the extent or result of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Watch Intently. Coadministration of fentanyl with CYP3A4 inducers could lead to a lessen in fentanyl plasma concentrations, insufficient efficacy or, quite possibly, improvement of a withdrawal sy… Read More