butabarbital will lower the level or impact of fedratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Steer clear of or Use Alternate Drug. Effect of coadministering a solid CYP3A4 inducer with fedratinib hasn't been researched.butabarbital will decrease the extent or effect of vardenafil by influencing hepatic/intestinal enzyme CYP3A