Pentobarbital will decrease the level or effect of alfentanil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. pentobarbital will decrease the level or effect of conjugated estrogens, vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. When barbiturates like Nembutal are abused, they are not usually the primary dr... https://bookmarkforce.com/story20393679/fascination-circa-pentobarbital-effects