pentobarbital will reduce the extent or impact of ethotoin by influencing hepatic enzyme CYP2C9/ten metabolism. Use Warning/Observe.pentobarbital boosts effects of ifosfamide by influencing hepatic enzyme CYP2B6 metabolism. Use Warning/Observe. Coadministration of ifosfamide with CYP2B6 inducers might boost metabolism of ifosfamide to its metabolit