Clopidogrel nonresponsiveness

Limited data are available to link clopidogrel nonresponsiveness to the occurrence of thrombotic events. Matetzky et al. studied clopidogrel responsiveness in patients undergoing stenting for acute ST-elevation Ml. They found that patients who exhibited the highest quartile of ADP-induced aggregation had a 40% probability for a recurrent cardiovascular... 

Reports of high incidences of aspirin resistance may be due to laboratory measurements based on nonspecific methods that do not isolate the response of platelet COX-1 to aspirin or due to an inadequate dose required to fully inhibit the COX-1 in selected patients. Clopidogrel nonresponsiveness is a consistent phenomenon observed in research studies conducted at multiple medical centers around the world. Data from small studies support that patients with high ex vivo platelet reactivity to ADP during and after percutaneous intervention may be at greatest risk for subsequent ischemic events. 

Mechanism of action of clopidogrel and laboratory evaluation of clopidogrel nonresponsiveness. (Seep. 145.)... 

All of the data mentioned earlier strongly support insufficient metabolite generation as the primary explanation for nonresponsiveness rather than genetic polymorphisms of platelet receptors or intracellular signaling mechanisms. The latter mechanisms may be relevant in those patients who may remain resistant and with high platelet reactivity to ADP even after treatment with high doses of clopidogrel. 

Sankyo Co. Ltd. Tokyo, Japan) is a new thienopyridine derivative that produces more potent platelet inhibition, and a rapid onset of action. The latter properties may provide a superior alternative to clopidogrel, with less response variability and a decreased prevalence of nonresponsiveness (I I I). 

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