Suppression by tetrandrine of human platelet aggregation induced by platelet-activating factor and other stimulants.

Tetrandrine was found to have inhibitory effects on platelet-activating factor induced platelet aggregation in a dose-dependent manner. There was preferential inhibition of platelet aggregation induced by agents such as collagen, thrombin, adrenaline, and adenosine diphosphate. No inhibitory effect of tetrandrine was observed on platelet aggregation induced by adenosine diphosphate, arachidonic acid, and the calcium ionophore A23187. These results support our previous findings of interference with the phosphatidylinositol second-messenger system as one of the sites of action of tetrandrine. Since platelets may have an important role in the pathogenesis of asthma and other allergic diseases, these findings suggest that tetrandrine may have clinical application as a non-steroidal broad-spectrum anti-allergic drug.