Cytochrome P450 3A5 Inhibitors

CYP3A5 is a cytochrome P450 monooxygenase that inserts one atom of molecular oxygen into its substrates - steroid hormones and vitamins - using two electrons supplied by NADPH through cytochrome P450 reductase. Drugs in this class reduce that catalytic activity, so a co-administered drug cleared by CYP3A5 is eliminated more slowly and accumulates. FDA grades the consequence by how far a sensitive index substrate's exposure rises, calling an inhibitor strong at a >=5-fold increase in AUC and moderate at >=2- to <5-fold. A drug belongs here because its recorded effect on CYP3A5 is inhibition, not induction.