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

• Published in: The American journal of cardiology Vol. 101; no. 9; pp. 1359 - 1363
• Main Authors: Qayyum, Rehan, MD, Becker, Diane M., MPH, ScD, Yanek, Lisa R., MPH, Moy, Taryn F., RD, MS, Becker, Lewis C., MD, Faraday, Nauder, MD, Vaidya, Dhananjay, MBBS, PhD, MPH
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.05.2008; Elsevier; Elsevier Limited
• Subjects: Adult; Aspirin; Aspirin - administration & dosage; Aspirin - pharmacology; Biological and medical sciences; Blood clots; Cardiology; Cardiology. Vascular system; Cardiovascular; Cardiovascular disease; Cardiovascular Diseases - blood; Cardiovascular Diseases - drug therapy; Clinical medicine; Comparative studies; Drug dosages; Female; Hematocrit; Humans; Lipids - blood; Logistic Models; Male; Medical sciences; Men; Middle Aged; Platelet Aggregation - drug effects; Platelet Aggregation Inhibitors - administration & dosage; Platelet Aggregation Inhibitors - pharmacology; Platelet Count; Platelet Function Tests; Sex Factors; Statistics, Nonparametric; Women; Human; Platelet; Cardiovascular disease; Acetylsalicylic acid; Circulatory system; Inhibition; Cardiology; Woman; Day; Comparative study
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/j.amjcard.2007.12.038

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.