STUDIES ON SUBCUTANEOUS ABSORPTION

Abstract

In spit.e of the universal practice of subcutaneous inject’ion in bot,h clinical and experimental work, review of the literature reveals no reference to a study of the rate and mechanism of absorption of subcutaneously injected substances. In an effort to throw light on these questions, det*erminations have been made as to the amounts of dihydroxyacetone, glucose, fructose, and galactose absorbed in a given time after subcut,aneous injection. METHOD. The method of procedure of these experiments was a,s follows : known amounts of the four substances, dihydroxyacetone, glucose, fructose, and galactose, were injected subcutaneously in a series of rat&s. The injections were made into the lumbar region using the Record type of syringe since it could be adjusted so that exactly the same volume, approximately 1 cc., could be injected each time. The same amount of solution was expressed into a flask and analyzed by the method of determinat(ion used throughout these experiments. In this way the exact amount of material injected into the rats was determined. The animals were sacrificed at varying periods after injection and the skin was dissected a*way to recover the unabsorbed material, which was then quantitatively determined. The amount absorbed was then calculated by subtracting the unabsorbed quant,ity from the total amount injected. These experiments consist of two series. In tlhe first series, 50 per cent solutions of the four substances were used. The animals were killed immediately and after fifteen, thirty, and forty-five minute periods of absorption. The determinations were performed by the Shaffer-Hsrtmsnn method. The results of the first series of experiments were such that it was deemed essential to perform a second series using more dilute solutions. Both 2.5 per cent and 5.0 per cent solutions of glucose were used. The recovered samples in the second series were analyzed by tlhe method of Hagedorn and Jensen (1923). Control injections of physiological saline were made in