Cytochrome P450 2A6; Cytochrome P450 2B6 (CYP2A6; CYP2B6)

Cytochrome P450 2A6 (CYP2A6) and Cytochrome P450 2B6 (CYP2B6) are microsomal enzymes principally expressed in the liver (and to a lesser extent, in extrahepatic tissues) that mediate the oxidative metabolism of a range of endogenous and exogenous compounds, notably nicotine, drugs such as bupropion, efavirenz, and cyclophosphamide, and various environmental chemicals[1][2][3][5][6]. Genetic polymorphisms in these enzymes explain significant inter-individual differences in drug metabolism and susceptibility to adverse drug reactions, influencing drug efficacy, toxicity, and personalized treatment approaches[2][4][6]. CYP2B6, in particular, is highly polymorphic, with over 38 known alleles; CYP2A6 also exhibits diversity across populations, especially in Asian and African groups[4]. Both enzymes are major targets for pharmacogenetic testing, biomarker development, and drug dosing guidance. Variability in function may contribute to diseases such as nicotine dependence and to differences in cancer drug metabolism[1][2][3][5][6].

Other names

Cytochrome P450 family 2 subfamily A member 6P450 2A6CYP2A6 geneCytochrome P450 family 2 subfamily B member 6P450 2B6CYP2B6 gene

Drugs are metabolized via C-oxidation, hydroxylation, and N-demethylation reactions catalyzed by CYP2A6 or CYP2B6. Polymorphic variation leads to altered drug clearance/metabolism rates (poor, intermediate, normal, rapid metabolizer phenotypes). Some drugs (e.g., bupropion, efavirenz) require dose adjustments based on CYP2B6 metabolic activity.