Inhibitory Effects of Ifenprodil Tartrate on Platelet Aggregation as Measuerd by the Particle Counting Method Using Light Scattering and Shear-Induced Platelet Aggregometer

Abstract

Ifenprodil tartrate, a cerebral vasodilator used for patients with a chronic cerebral infarction, is known to inhibit platelet aggregation. We have studied the mechanism of its inhibition of platelet aggregation by utilizing the particle-counting method using light scattering and a shear-induced platelet aggregometer.
Ifenprodil was found to inhibit both epinephrine-induced platelet aggregation, and shear-induced and epinephrine-enhanced platelet aggregation. When epinephrine was replaced with brimonidine, a selective platelet α₂ adrenoceptor agonist, similar inhibition by ifenprodil was observed. As the inhibition profiles were similar to those by yohimbine, our results altogether seem to indicate that ifenprodil may inhibit platelet aggregation via inhibition of the platelet α₂ adrenoceptor.