pentobarbital will lessen the level or influence of fentanyl intranasal by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep track of Intently. Coadministration of fentanyl with CYP3A4 inducers may lead to the lessen in fentanyl plasma concentrations, lack of efficacy or, maybe, advancement of the withdrawal syndrome in a