Genotyping of CYP2C19 helps to reassure sufficient effects of antiplatelet therapy in combination with proton pump inhibitors (PPIs)

Clopidogrel therapy in combination with proton pump inhibitors (PPIs) is controversial in the treatment for ischemic heart diseases after coronary stent implantation because PPIs (especially omeprazole) are suggested to attenuate the antiplatelet effect of clopidogrel. The polymorphic CYP2C19 enzyme has a pivotal function in the metabolism of both agents. In addition, omeprazole can irreversibly inhibit the activity of CYP2C19 enzyme. The frequency of CYP2C19 polymorphisms with a poor metabolizer phenotype is especially high (29-35%) in the Asian population. The present study investigated whether CYP2C19 genotyping is required in clopidogrel-treated patients with concomitant omeprazole treatment for genetically at risk poor metabolizing CYP2C19 populations. In this study literature was searched and reviewed which comprised the specific research area. The results indicated that omeprazole in combination with clopidogrel is related to a higher recurrence risk of adverse cardiovascular events and a higher mortality rate. Interestingly, the antiplatelet effect of clopidogrel was more affected by omeprazole in homozygous CYP2C19*1 carries than in heterozygous (*1/2 or *1/3) and homozygous (*2/2 or *2/3) CYP2C19 carriers. Therefore, CYP2C19 genotyping is advised in clopidogrel-treated patients with concomitant omeprazole treatment. This to prevent adverse cardiovascular events in clopidogrel treated patients in combination with PPIs. However, the number of studies is rather limited up till now in relation to the CYP2C19 status and the combination of omeprazole plus clopidogrel. Therefore further clinical studies are indispensable to verify the conclusion in this study.