Aspirin: dose and indications in modern stroke prevention.

Until recently, a gap existed between the rapidly advancing knowledge about the pharmacology of aspirin and the management of patients who are threatened by stroke. In doses as low as 20 to 40 mg per day, aspirin can completely suppress the production of the aggregant agent thromboxane A2. The clinical evidence, however, which shows a reduction of 20% to 25% in the incidence of vascular death, stroke, or myocardial infarction, is based on trials with 300 to 1300 mg of aspirin per day. The clinicians are catching up now that recent trials have demonstrated similar effects with 30 or 75 mg of aspirin per day, and with fewer side effects. The hope that the protective effects of these low doses would be even greater, thanks to the sparing of the prostaglandin synthesis in endothelial tissue, has not yet materialized.