Clopidogrel inhibits shear-induced platelet function.

We enrolled 17 healthy adult volunteers and measured platelet hemostasis time (PHT) and collagen-induced thrombus formation (CITF) before and after the oral administration of 300 mg of clopidogrel utilizing the Xylum Clot Signature Analyzer. We documented a statistically significant 30% prolongation of the PHT from 291+/-13 (SE) seconds to 376+/-31 (SE) s (P=0.037). There was a 7% prolongation of the CITF from 347+/-10 to 371+/-17 (SE) s (P=0.245). This study suggests that the Xylum Clot Signature Analyzer can measure changes in platelet function in response to a modest platelet inhibitor, and may be a useful clinical tool for the monitoring of antiplatelet therapies in patients.