The relationship between the degradation of prostacyclin in blood and antiplatelet drug effects in patients with atherosclerosis.

Blood and plasma from 109 patients with atherosclerosis and 70 healthy volunteers were tested to study the rate of prostacyclin (PGI2) hydrolysis. It has been reported that patients with atherosclerosis have the enhanced velocity of PGI2 degradation. The increase in the velocity was more marked in blood than in plasma. The significant negative correlation between antiaggregation effects of pentoxifylline, nifedipine, and dipyridamole and the velocity of PGI2 degradation in the patients was found. These data suggest that the increase of PGI2 biosynthesis by the drugs studied can enhance their antiaggregation effect if processes of PGI2 degradation in blood are not accelerated.