Pentobarbital will lower the level or effect of tamoxifen by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Check. pentobarbital will lower the extent or influence of saxagliptin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. pentobarbital will decrease the extent or influence of alosetron by impacting hepatic/intestinal enzym... https://citychemiststore.com/product/buy-nembutal-powder-online/