pentobarbital will reduce the extent or effect of theophylline by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch.pentobarbital decreases amounts of toremifene by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Watch. CYP3A4 inducers maximize amount of toremifene metabolism, decreasing the continual-point