Sulfinpyrazone decreases epinephrine-induced platelet aggregation after myocardial infarction

Platelet studies were performed during a controlled double-blind randomized clinical trial of sulfinpyrazone (Anturane Reinfarction Trial) in 41 patients who had recent myocardial infarction. Aggregation of platelet-rich plasma by thrombin (0.185, 0.246 U/ml), collagen, adenosine diphosphate, and adrenaline (0.23, 0.46, and 0.91 microgram/ml) was estimated after a 12 hour fast including abstinence from drugs and cigarette smoking. The tests were carried out 2 weeks after myocardial infarction and 6, 12, and 24 months later. At the last visit, washed platelet suspensions were also tested for aggregation to thrombin (0.03, 0.015 U/ml) +/- epinephrine (0.55 microgram/ml) and their production of malonyldialdehyde was estimated. A significant (p less than 0.02) reduction (50%) of the aggregation response of platelet-rich plasma to epinephrine was found in the group treated with sulfinpyrazone (n = 21) as compared with the placebo group (n = 20). Also, adrenaline evoked a milder (p less than 0.01) potentiation of aggregation by thrombin of the washed platelet suspensions in the sulfinpyrazone versus the placebo group. Other assays including platelet coagulant activity were not useful in discriminating between the 2 groups. It is concluded that sulfinpyrazone (200 mg 4 times daily) normalizes the platelet response to epinephrine; a relation with the drug-reported reduction of sudden death after myocardial infarction is suggested.