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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Anesthesiology. 2011 Dec;115(6):1316–1327. doi: 10.1097/ALN.0b013e3182315eb2

Figure 4.

Figure 4

Effects of CYP2D6 genotype on CYP2D6 substrate metabolism. Extensive metabolizers (EM) have one or two normal copies of the CYP2D6 gene and are considered wild-type. A normal β-blocker dose will likely result in a therapeutic drug concentration. Ultra-rapid metabolizers (UM) possess more than 2 functional copies (up to 13). A CYP2D6 substrate (e.g., metoprolol) will be rapidly metabolized and the drug effect minimal. Intermediate metabolizers (IM) have one or two hypo-functional CYP2D6 alleles which results in a reduced CYP2D6 function. Substrate metabolism is reduced and higher drug concentrations result with the possibility of an exaggerated response. Poor metabolizers (PM) have two nonfunctional copies of CYP2D6 which results in a nonfunctional enzyme. This may lead to toxic drug concentrations.