pentobarbital raises toxicity of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Observe. CYP3A4 inducers may perhaps boost the metabolism of ifosfamide to its Lively alkylating metabolites.pentobarbital will decrease the extent or influence of etonogestrel by impacting hepatic/intestinal enzyme CYP3A4 metabolism. U