Inhibition of Aggregation of Human and Rat Platelets By Fibrinolytic Drug Phenformin

Aggregation of human platelets by ADP, adrenaline and collagen was inhib ited by phenformin in citrated plasma. As low as 12.5 μg/ml final concentration of phenformin resulted 50% inhibition of adrenaline induced aggregation of platelets. Platelet aggregation induced by ADP was greatly enhanced by adren aline in citrated plasma of rat. Applied in low concentration phenformin dimin ished the adrenaline-induced increased sensitivity of rat platelets to ADP. Phenformin is an oral antidiabetic drug, the effectiveness of which to increase fibrinolytic activity of blood have been established by Fearnley and Chakra barti (1) and supported by Isacson and Nilsson (2). Besides antidiabetic and fibrinolytic activity Phenformin has a blood cholesterol level lowering effect (3). Phenformin in combination with ethyloestrenol proved to be effective in the treatment of various occlusive vascular diseases (4). In human subjects the drug-combination decreased the adhesiveness of platelets to glass beads but Phenformin alone was without effect (4). We have not found any data concern ing the effect of Phenformin on aggregation of platelets of the blood of humans or experimental animals. Because the importance of platelet aggregation and plug formation in hemostasis and thrombosis has been well established, it seemed interest to investigate the effect of Phenformin from this aspect.