butabarbital will lower the level or impact of fedratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Stay away from or Use Alternate Drug. Effect of coadministering a powerful CYP3A4 inducer with fedratinib hasn't been studied.butabarbital will lessen the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4