Abstract
Experimental evidence obtained both in the laboratory 1 and in the clinic 2 shows that the borate of diethylamino ethyl p-amino-benzoate, procaine borate, has a higher anesthetic efficiency than the hydrochloride of the same base. The fact that the solutions of procaine borate used had a pH of about 8.4 while the procaine hydrochloride solutions had a pH of approximately 5.6 suggested that it might be worth while to determine the effect of variation of pH on the anesthetic efficiency of the two drugs.
O. Gros 3 found that addition of excess sodium bicarbonate or secondary sodium phosphate markedly increases the anesthetic efficiency of procaine hydrochloride. Sollmann 4 corroborated and extended these findings. Regnier, 5 from his results on alkalinization of cocaine hydrochloride solutions, also concluded that increase in alkalinity augments anesthetic properties.
The present work consisted in a comparison of the anesthetic efficiency of procaine borate and procaine hydrochloride solution at varying hydrogen ion concentrations by the method of Adams 6 on goldfish with modifications suggested by Dailey 7 and Benedict. The solutions used were brought to the desired pH with N/10 sodium hydroxide and N/10 hydrochloric acid. The pH determinations were made with a Leeds-Northrup Quinhydrone potentiometer. All solutions used were of the same concentration with respect to the anesthetic base, the procaine hydrochloride solutions containing 1 gm. of the hydrochloride in 500 cc. of solution and the procaine borate solutions containing 1.638 gm. of the borate in 500 cc. of solution.
The results obtained are given in the graph. Each point represents the average time required to anesthetize 3 or more fish, anesthesia being determined by lack of response to stimulation of fins or tail.
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