Keep track of Carefully (one)oxcarbazepine will lower the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Observe Carefully. Coadministration of fentanyl with CYP3A4 inducers may lead to the reduce in fentanyl plasma concentrations, deficiency of efficacy or, probably, development of the withdraw