pentobarbital decreases amounts of toremifene by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch. CYP3A4 inducers increase fee of toremifene metabolism, lowering the regular-condition focus in serum.pentobarbital will lower the level or influence of tadalafil by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use W