Cytochrome P450 3A Inhibitors

CYP3A4 and CYP3A5 are the cytochrome P450 monooxygenases of the CYP3A subfamily that this class is named for: each inserts one atom of molecular oxygen into its substrate and reduces the second to water, with two electrons supplied by NADPH through cytochrome P450 reductase. CYP3A4 metabolises sterols, steroid hormones, retinoids and fatty acids; CYP3A5 metabolises steroid hormones and vitamins. Drugs in this class reduce that catalytic activity, so a co-administered drug cleared by CYP3A 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 or greater increase in AUC and moderate at 2- to under 5-fold. A drug belongs here because its recorded effect on CYP3A is inhibition, not induction; as MED-RT populates the class its members include cobicistat, the protease inhibitors boceprevir, telaprevir, simeprevir and grazoprevir, idelalisib, osimertinib, letermovir, conivaptan, lomitapide, levoketoconazole and the ergot alkaloids.