Platelet response to aspirin in Chinese stroke patients is independent of genetic polymorphisms of COX-1 C50T and COX-2 G765C

Aim: aspirin resistance (ar) is common in chinese stroke patients taking antiplatelet medications; however,few studies have documented the role of cyclooxygenase (cox)-1 c50t and cox-2 g765c polymorphisms in ar. the aim of this study was to investigate the prevalence of ar in chinese stroke patients and the relationships between ar and cox-1 c50t and cox-2 g765c polymorphisms,and to evaluate the effect of these polymorphisms on platelet response to aspirin. methods: we prospectively enrolled 634 chinese stroke patients. platelet aggregation testing was performed before and after aspirin administration. the pre- and post-aspirin levels of 11-dehydrothromboxane b2 (11-dtxb2) were determined in urine samples. cox-1 c50t and cox-2 g765c genotypes were determined by a polymerase chain reaction-allelic restriction assay. results: ar was detected in 129 patients (20.4%),aspirin semi-resistance (asr) was detected in 28 patients (4.4%),and aspirin sensitivity (as) was detected in 477 patients (75.2%). there was no association between cox-1 c50t or cox-2 g765c polymorphisms and asr+ar. aspirin could efficiently reduce 11-dtxb2 production by approximately 75%. in addition,platelet aggregation,both in response to arachidonic acid (aa) and adenosine 5'-diphosphate (adp),was inhibited by more than 80% and 40%,respectively; however,the percentage reduction in platelet aggregation and 11-dtxb2 levels was not significantly different between the cox-1 c50t and cox-2 g765c genotypes (p>0.05). conclusions: there was no association between cox-1 c50t and cox-2 g765c polymorphisms and ar in chinese stroke patients. in addition,cox-1 c50t and cox-2 g765c polymorphisms had no effect on the platelet response to aspirin.