pentobarbital will lessen the level or outcome of tamoxifen by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Keep an eye on.pentobarbital raises toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Warning/Watch. CYP3A4 inducers may perhaps improve the metabolism of ifosfamide to its Lively alkyl