butabarbital will reduce the extent or outcome of zonisamide by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Insignificant/Importance Mysterious.butabarbital improves effects of ifosfamide by affecting hepatic enzyme CYP2B6 metabolism. Use Warning/Observe. Coadministration of ifosfamide with CYP2B6 inducers might increase metabolism of