Cytochrome P450 family 3 subfamily A member 4 (CYP3A4) and Cytochrome P450 family 2 subfamily C member 19 (CYP2C19) (CYP3A4 and CYP2C19)

Cytochrome P450 3A4 (CYP3A4) and Cytochrome P450 2C19 (CYP2C19) are two of the most significant enzymes in the human cytochrome P450 superfamily, responsible for the Phase I metabolism of approximately 50% and 10-15% of clinically used drugs, respectively [1, 2]. CYP3A4 is predominantly expressed in the liver and small intestine, where it oxidizes a vast array of structurally diverse compounds, including macrolide antibiotics, azole antifungals, and statins [1, 3, 5]. CYP2C19 is also primarily hepatic and is critical for the activation of prodrugs like clopidogrel and the metabolism of proton pump inhibitors and certain antidepressants [2, 4, 6]. Both enzymes exhibit significant genetic polymorphism, particularly CYP2C19, which leads to wide inter-individual variability in drug response and risk of toxicity [4, 6]. Because many drugs are substrates, inhibitors, or inducers of these enzymes, they are central to the study of drug-drug interactions (DDIs) and personalized medicine [1, 6]. These enzymes are often evaluated together in polypharmacy contexts to predict potential adverse reactions and optimize therapeutic outcomes [5, 6].

Other names

Cytochrome P450 3A4Cytochrome P450 2C19Nifedipine oxidaseS-mephenytoin 4'-hydroxylaseCYP3A3P450C2CP450-PCN1P450-11

These enzymes act as monooxygenases in the Phase I metabolism of drugs, where they utilize heme-bound iron and molecular oxygen to catalyze the oxidation of substrates, typically via hydroxylation, N-dealkylation, or O-dealkylation [1, 2].