pentobarbital will lower the level or impact of tamoxifen by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Check.Keep an eye on Carefully (1)pentobarbital will minimize the level or influence of fentanyl by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration of fentanyl with