Effect of Dipyridamole and Two Pyrimido-Pyrimidine Derivatives on the Kinetics of Human Platelet Aggregation and on Platelet Adhesiveness

Abstract

Dipyramidole and two new derivatives (RA 233 and 433) were compared as regards their inhibitory action on ADP- and noradrenaline-induced platelet aggregation and adhesiveness in vitro. Aggregation was studied with a turbidometric method allowing accurate kinetic studies. Platelet adhesiveness and aggregation were markedly inhibited by RA 233 and RA 433 (5–50 μg/ml) while dipyridamole (50–100 μg/ml) only had a weak and irregular effect. The rate of disaggregation was not influenced.