Effect of variable doses of aspirin on platelet functions.

Serial platelet functions were studied after various single doses of aspirin (75 mg, 150 mg, 300 mg, and 600 mg) in 20 males. Clotting time and platelet counts remained unchanged. Significant deaggregation of platelets occurred only with 600 mg of aspirin. This persisted on day '3'. Platelet factor-3 release time was prolonged till day '3' with only 150 mg and 600 mg doses of aspirin. In view of these findings it appears that 600 mg aspirin given every 4th day is more suited for significant antiplatelet effect.