Cytochrome P450 1A Inducers

The CYP1A subfamily comprises CYP1A1 and CYP1A2, cytochrome P450 monooxygenases that oxidise fatty acids, steroid hormones and vitamins as well as many xenobiotics, inserting one atom of molecular oxygen into the substrate and reducing the second to water with two electrons supplied by NADPH through cytochrome P450 reductase. Drugs in this class induce that activity - UniProt records CYP1A1 as induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and CYP1A2 as induced by nicotine, omeprazole, phenobarbital, primidone and rifampicin - so substrates of the subfamily are cleared faster and their exposure falls. FDA grades that consequence and defines an inducer by it: strong and moderate index inducers decrease the AUC of sensitive substrates of a given metabolic pathway by at least 80 percent and by 50 to under 80 percent respectively. A drug belongs here because its recorded effect on CYP1A is induction, not inhibition; as MED-RT populates the class, its one member is osimertinib.