pentobarbital decreases levels of toremifene by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Watch. CYP3A4 inducers boost rate of toremifene metabolism, decreasing the steady-point out focus in serum.pentobarbital will lower the extent or influence of tamoxifen by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Use Wa