Platelet Inhibition by Aspirin 81 and 325 mg/day in Men Versus Women Without Clinically Apparent Cardiovascular Disease

Rehan Qayyum, Diane M. Becker, Lisa R. Yanek, Taryn F. Moy, Lewis C. Becker, Nauder Faraday, Dhananjay Vaidya

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Compared with men, women have greater platelet aggregation before and after low-dose aspirin. It is not known whether high-dose aspirin therapy brings residual platelet aggregation in women closer to that in men. Our objective was to compare inhibition of platelet aggregation in women and men after low- and high-dose aspirin. We enrolled healthy subjects (n = 106) in a trial of 14 days of aspirin 81 mg/day followed by 14 days of 325 mg/day. Platelet function was measured at baseline and after the 2 aspirin doses. Women had greater baseline platelet activation measurements. After the 2 aspirin doses, men and women had near complete suppression of platelet aggregation to arachidonic acid in whole blood and in platelet-rich plasma (PRP), the direct cyclo-oxygenase-1 pathway affected by aspirin. For indirect pathways, women had significantly greater residual platelet activation to collagen and adenosine diphosphate (ADP) in whole blood after the 2 aspirin doses and in response to collagen and ADP in PRP after aspirin 325 mg/day only. After aspirin 325 mg/day, women continued to have greater residual platelet aggregation compared with men after aspirin 81 mg/day in response to collagen (p = 0.016 in whole blood, p = 0.037 in PRP), ADP (p <0.001 in whole blood, p = 0.012 in PRP), and epinephrine (p = 0.03 in PRP). Excretion of urinary thromboxane metabolite (urinary 11-dehydrothromboxane B2) decreased after aspirin to a similar extent in men and women. In conclusion, women continue to have greater residual platelet activity after high-dose aspirin compared with men treated with a lower dose of aspirin.

Original languageEnglish (US)
Pages (from-to)1359-1363
Number of pages5
JournalAmerican Journal of Cardiology
Issue number9
StatePublished - May 1 2008

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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