Keep track of Carefully (1)pentobarbital will minimize the level or outcome of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Carefully. Coadministration of fentanyl with CYP3A4 inducers could lead to a lessen in fentanyl plasma concentrations, not enough efficacy or, possibly, growth of the wit