Effect of incremental doses of aspirin on bleeding time, platelet aggregation and thromboxane production in patients with cerebrovascular disease.

Bleeding time, thromboxane production and inhibition of platelet aggregation were studied before and during administration of acetylsalicylic acid in doses of 50, 100, 325 an 1000 mg daily in eighteen patients with cerebrovascular disease. Inhibition of thromboxane production and platelet aggregation was almost complete at 50 mg acetylsalicylic acid daily, and median bleeding time had increased significantly from 5.5 to 6.5 min at this dose and reached a maximum of 7.5 min at 100 mg daily. Further increase of the dose resulted in a slight decrease in bleeding time. It appears that a strong effect on platelet function can be achieved by small doses of acetylsalicylic acid, and that higher doses might be less effective.