genetic polymorphisms of cyp2c19 and their importance in clopidogrel antiplatelet therapy

background: clopidogrel is one of the most commonly prescribed drugs to prevent ischemic events following coronary syndromes or stent placement. however, impaired responses to therapy as well as resistance are also reported. genetic variants play an important role in clopidogrel biotransformation to its active metabolite that may subsequently influence the clopidogrel antiplatelet effect. the objective of this study was to evaluate the prevalence of the cytochrome p450 (cyp450) 2c19 enzyme (cyp2c19) genotypes which are involved in activation of clopidogrel in the iranian population. molecular analysis of cyp2c19 polymorphisms may be helpful in determination of optimal antiplatelet therapy. materials and methods: cyp2c19 (*1/*2/*3) variants were assessed by polymerase chain reaction-restriction length polymorphism (pcr–rflp) assays in a representative sample of 154 iranian patients with ischemic heart disease. results: the frequencies of cyp2c19 *1 (normal genotype), *2 (heterozygote) and *3 (homozygote) were 112 (72.7%), 36 (23.4%) and 6 (3.9%), respectively. conclusions: fda recommendations are more useful to be practiced in our country than other countries. physicians should identify poor metabolizers for consideration of other antiplatelet medications or alternative dosing strategies.