Observe Carefully (1)istradefylline will improve the degree or outcome of diazepam by impacting hepatic/intestinal enzyme CYP3A4 metabolism.enasidenib will boost the amount or influence of diazepam by affecting hepatic enzyme CYP2C19 metabolism. Use Warning/Monitor. Enasidenib (a weak CYP2C19 inhibitor) may raise systemic exposure of delicate CYP2C