Studies on Local Anesthetics. III

On the Alkylaminoacetanilides Containing Thioalkyl Substituents

Abstract

In order to find the effect of thioalkyl group introduced into a benzene nucleus on local anesthetic properties, 15 kinds of alkylaminoacetanilide substituted in the ortho and para positions with thioalkyl group were prepared and their local anesthetic properties were compared. In general, the anesthetic action increased with the increase of the number of carbon atoms in the thioalkyl group, with attendant increase in toxicity. The maximum efficacy was found in p-thioamyldiethylaminoacetanilide which possessed 2.3 times the surface anesthetic power of cocaine. These substances possess a certain amount of local irritating action, similar to the corresponding alcoxyl compounds, but it was observed that their anesthetic properties are slightly better than those of oxygen compounds. Reduction of alcoxyl compounds, to decrease irritating action, to hydroxyl derivatives resulted in the loss of local anesthetic action together with the decrease of irritating properties.