Observe Intently (1)pentobarbital will reduce the level or outcome of fentanyl transdermal by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Keep an eye on Closely. Coadministration of fentanyl with CYP3A4 inducers could lead to the lessen in fentanyl plasma concentrations, insufficient efficacy or, perhaps, improvement of th