Long-term ultra-low-dose aspirin therapy and platelet function.
The effect of ultra-low-dose aspirin on platelet aggregation and thromboxane B2 (TXB2) production was studied in two groups of normal subjects. Group 1 received 162 mg/d and group 2 received 20 mg/d for 4 weeks. For the first 2 weeks the effects were similar in the two groups, namely inhibition of aggregation and inhibition of TXB2 production. However, after 4 weeks there was significantly less inhibition of platelet aggregation in those receiving 20 mg/d. Inhibition of TXB2 production in the two groups was not significantly different. Two of 9 individuals receiving 20 mg/d showed an escape from the aspirin effect by the 4th week. When 40 mg/d was given to these 2 individuals they again responded. A daily dose of 20 mg aspirin is therefore too small to maintain adequate inhibition of platelet function in normal subjects.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000008:administration & dosage / Q000494:pharmacology*; D001760:Bleeding Time; D003094:Collagen / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D013929:Thromboxane B2 / Q000097:blood*; D013931:Thromboxanes / Q000097:blood*; D013997:Time Factors
D001095:Arachidonic Acids; D013931:Thromboxanes; D016718:Arachidonic Acid; D013929:Thromboxane B2; D000244:Adenosine Diphosphate; D003094:Collagen; D001241:Aspirin; D004837:Epinephrine