Why the study?
Do single doses of commonly used anti-platelet drugs affect bleeding time and platelet aggregation in normal human subjects?
Do single doses of commonly used anti-platelet drugs affect bleeding time and platelet aggregation in normal human subjects?
Standard single doses of many commonly used 'anti-platelet' drugs, other than aspirin, have little clinical effect on in-vivo hemostasis in normal subjects, suggesting in-vitro results may not directly apply in-vivo.
Aspirin alone among single-dose agents prolongs bleeding time in normals; challenges in-vitro to in-vivo translation for other antiplatelet drugs.
The effects on hemostasis of several commonly used drugs previously described as inhibiting platelet function were evaluated in a randomized, double-blind study of 54 normal volunteers. The subjects were each given a single dose of aspirin, chlorpromazine, glyceryl guaiacolate, diphenhydramine, indomethacin or lactose placebo. A single dose of aspirin significantly prolonged the template bleeding time and inhibited secondary platelet aggregation two and 24 hours after ingestion. Single doses of indomethacin and chlorpromazine affected aggregation at two hours but had no effect on bleeding time, although multiple doses of indomethacin did prolong bleeding time. Glyceryl guaiacolate inhibited aggregation one hour after ingestion but had no effect on bleeding time. Diphenhydramine did not affect either. These findings suggest that standard doses of many commonly used "anti-platelet" drugs may have little clinical effect on the hemostatic mechanism in normal man. Results of in-vitro platelet-drug incubations may not be directly applicable to in-vivo hemostasis.
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Buchanan et al. (1977) studied this question.
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