The effect of dipyridamole on adenosine uptake by platelets [formula omitted

Abstract

The inhibition of adenosine uptake by human platelets in the presence of dipyridamole was measured under ex vivo and in vitro conditions. The uptake of [ 14C]-adenosine by platelets from 12 human volunteers given various dosages of dipyridamole (0.48 to 3.6 mg/kg body weight) correlated with the concentration of the drug in the plasma. On the average, the concentrations of dipyridamole required to produce 50% inhibition of adenosine uptake under in vitro and ex vivo conditions were 0.22 μM and 0.17 μM, respectively. The inhibition of adenosine uptake by platelets of rabbits injected with dipyridamole also correlated with the dosage given. It is suggested that the pharmacological action of dipyridamole on the platelets can be monitored by measuring dipyridamole level in plasma and 14C adenosine uptake by the platelets.