Aspirin administered to women at 100 mg every other day produces less platelet inhibition than aspirin administered at 81 mg per day: implications for interpreting the women's health study.

Objective: We aimed to determine the relative level of platelet inhibition achieved with low-dose aspirin (81 mg daily) compared with a very low-dose (100 mg every other day).

Background: The Womens Health Study (WHS) found that a dose of 100 mg every other day of aspirin provided protection against stroke as primary prophylaxis, but not myocardial infarction. In the United States, the most commonly prescribed dose of aspirin for primary prophylaxis is 81 mg per day.