Equivalent inhibition of in vivo platelet function by low dose and high dose aspirin treatment

Abstract

In vitro platelet function was inhibited in healthy volunteers by two different doses of aspirin, as confirmed by measurement of maximum serum production of thromboxane B 2 (TXB 2) by platelets. 75 mg aspirin did not fully inhibit serum TXB 2 production after 24 hours, whereas 300 mg aspirin did. Inhibition of platelet function in vitro was maintained by both 75 mg/day aspirin or 300 mg/alternate day aspirin. In contrast, in vivo production of TXB 2, measured as urinary levels of the 11-keto-TXB 2 metabolite, was inhibited similarly by both doses of aspirin throughout the study. These findings suggest that 75 mg/day aspirin may be sufficient adequately to inhibit platelet aggregation in vivo.