Study Compares Every-Third-Day vs Daily Low-Dose Aspirin Effects on Thromboxane Inhibition

Aspirin's antithrombotic effect is mediated predominately by inhibition of platelet cyclooxygenase-1, leading to a decline in serum thromboxane A2 concentrations.

We performed a placebo-controlled, randomized, double-blind trial to determine whether aspirin could be given at 3-day intervals and still achieve potent serum thromboxane inhibition.

One hundred nine healthy men and women with no recent exposure to aspirin or other nonsteroidal anti-inflammatory drugs were randomized to receive either placebo, aspirin 81 mg daily, or aspirin 81 mg every third day for 28 days.

Serum thromboxane B2 concentrations were measured at baseline and on days 14 and 28.

Both aspirin regimens resulted in >95% inhibition of serum thromboxane B2 compared with placebo, with no significant difference between daily and every-third-day dosing.