Effects of aspirin on platelet aggregation as a function of dosage and time.

There are reports on the effects of high doses of aspirin on the alteration of platelet aggregation. In our study single doses of aspirin ranging from 81 to 325 mg were given orally to 7 normal subjects. In vitro measurement of platelet aggregation was carried out as a function of time. Based on our data we conclude that low-dose aspirin (81 mg) inhibits platelet aggregation. Both the rate and extent of platelet aggregation are impaired with low-dose aspirin, but neither the rate nor extent of platelet aggregation depends on the size of the dose. Platelet aggregation inhibition by a single dose of aspirin orally (greater than or equal to 81 mg) may be expected to persist for the life of the platelets affected.