1. Drug-metabolizing enzymes that exhibit clinically relevant genetic polymorphisms. Essentially all of the major human enzymes responsible for modification of functional groups (classified as phase I reactions [left]) or conjugation with endogenous substituents (classified as phase II reactions [right]) exhibit common polymorphisms at the genomic level; those enzyme polymorphisms that have already been associated with changes in drug effects are separated from the corresponding pie charts. The percentage of phase I and phase II metabolism of drugs that each enzyme contributes is estimated by the relative size of each section of the corresponding chart. ADH, alcohol dehydrogenase; ALDH, aldehyde dehydrogenase; CYP, cytochrome P-450; DPD, dihydropyrimidine dehydrogenase; NQO1, NADPH, quinone oxidoreductase or DT diaphorase; COMT, catechol O-methyltransferase; GST, glutathione S-transferase; HMT, histamine methyltransferase; NAT, N-acetyltransferase; STs, sulfotransferases; TPMT, thiopurine methyltransferase; UGTs, uridine 5′-triphosphate glucuronosyltransferases. (From Evans and Relling, 1999, with permission.)
Source: Pharmacogenetics and Drug Metabolism, Applied Biopharmaceutics & Pharmacokinetics, 7e
Citation: Shargel L, Yu AC. Applied Biopharmaceutics & Pharmacokinetics, 7e; 2016 Available at: Accessed: October 20, 2017
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