pentobarbital will lower the extent or effect of fentanyl intranasal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep track of Carefully. Coadministration of fentanyl with CYP3A4 inducers may lead to the reduce in fentanyl plasma concentrations, lack of efficacy or, maybe, development of the withdrawal syndrome in a aff