The great increase in the use of spinal anesthesia during the past two decades has been accompanied by a corresponding increase in the number of studies relating to its clinical aspects. But the basic question of the dynamics and fate of the drug itself has not been adequately treated. We therefore embarked on a program designed to develop and utilize trustworthy technics which would enable us to trace the course of the drug, determine what changes, if any, it underwent and find the site and the mechanism of these changes. While this program has not been completely fulfilled, we believe sufficient information has been gained to assist materially in the understanding of spinal and local anesthesia induced by procaine hydrochloride.
The first step was the development of a delicate analytic method for the determination of procaine in the various body fluids. Since it soon appeared that the procaine is rapidly