pentobarbital will lessen the extent or impact of fentanyl intranasal by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep track of Carefully. Coadministration of fentanyl with CYP3A4 inducers could lead on to a lessen in fentanyl plasma concentrations, not enough efficacy or, probably, advancement of a withdrawal syndrom