Pentobarbital will decrease the level or effect of vinblastine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown. pentobarbital will decrease the level or effect of nateglinide by affecting hepatic enzyme CYP2C9/10 metabolism. Use Caution/Monitor. pentobarbital will decrease the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP... https://jacko023jki6.jasperwiki.com/user