Abstract

A variety of drugs affecting the central nervous system have the ability to inhibit platelet aggregation, presumably by stabilizing the platelet membrane and preventing transmembrane flux of adenosine diphosphate and calcium ion. Low concentrations of local anesthetics stabilize red blood cell membranes and prevent hemolysis, while higher concentrations actually induce hemolysis. We studied the effect of lidocaine, bupivacaine, tetracaine, and chloroprocaine on platelet aggregation. Low concentrations in pharmacologic range, had little effect, while higher concentrations significantly inhibit aggregation. The first detectable alteration in the platelet aggregation curve was a prolongation of the lag period in the collagen-induced curve which is interpreted as indicating decreased platelet membrane permeability. While significant abnormalities in platelet aggregation do not occur with clinically-obtained blood levels of local anesthetics, the platelet may represent a readily available, easily replaced human model for studying the effects of local anesthetics on cell membranes.