pentobarbital will lower the level or influence of fosphenytoin by impacting hepatic enzyme CYP2C9/10 metabolism. Use Warning/Observe.pentobarbital will lessen the extent or result of clarithromycin by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Small/Significance Unfamiliar.pentobarbital will lessen the extent or impact of phenytoin b