Cytochrome P450 family 1 subfamily A member 2 (CYP1A2), Cytochrome P450 family 2 subfamily C member 9 (CYP2C9), and Cytochrome P450 family 3 subfamily A member 4 (CYP3A4) (CYP1A2, CYP2C9, CYP3A4)

The Cytochrome P450 (CYP) enzymes 1A2, 2C9, and 3A4 are the most significant members of the CYP superfamily involved in human drug metabolism [5]. Located primarily in the endoplasmic reticulum of hepatocytes and enterocytes, these heme-containing monooxygenases facilitate the Phase I biotransformation of approximately 70-80% of clinical drugs [4]. CYP3A4 is the most abundant isoform and possesses a large, flexible active site allowing it to metabolize a vast array of structurally diverse compounds, including statins and immunosuppressants [3]. CYP2C9 is critical for the clearance of drugs with narrow therapeutic indices, such as warfarin and phenytoin, and is highly polymorphic [2]. CYP1A2 is involved in the metabolism of caffeine and the bioactivation of several environmental pro-carcinogens [1]. Together, these enzymes are the primary determinants of pharmacokinetic variability, drug-drug interactions, and individual susceptibility to adverse drug reactions [5].

Other names

CYP1A2CYP2C9CYP3A4Cytochrome P450 1A2Cytochrome P450 2C9Cytochrome P450 3A4P450(I)A2P450-HLPNifedipine oxidase

These enzymes catalyze the oxidative metabolism (Phase I) of diverse substrates through the activation of molecular oxygen and the insertion of one oxygen atom into the substrate (monooxygenation) [5].