Effects of intermittent treatment with aspirin on thromboxane and prostacyclin formation in patients with acute myocardial infarction.

Thromboxane and prostacyclin formation were monitored in twenty patients with acute myocardial infarction. Ten received 500 mg acetylsalicylic acid (ASA) orally starting 12 h after admission and then intermittently every third day for one month; the other ten did not receive ASA or any other drug known to interfere with the synthesis of prostanoids. In the ASA group thromboxane formation, initially raised, fell rapidly and remained low. In the control group thromboxane formation decreased very slowly and was not normal by the end of the study period. Prostacyclin formation seemed identical in the two groups. Thus intermittent ASA, in this dosage, efficiently inhibited the enhanced thromboxane formation in acute myocardial infarction without interfering with prostacyclin formation.