On the Rate of Absorption from Intramuscular Tissue

The rate of absorption from muscles has never yet been a subject of scientific investigation. In fact, nowhere in physiological li terature do we meet the suggestion tha t absorption from the muscles might differ from tha t of any other parenchymatous or subcutaneous tissue. Only from the serous cavities, especially the peritoneal, is it generally assumed tha t absorption takes place more rapidly than from the subcutaneous tissues. In the recent extensive studies of infections and immunity, in which inoculation of animals with virulent, toxic, or antitoxic material is one of the most extensively employed methods of investigation, this is usually accomplished by subcutaneous or intraperitoneal injections, t o which injections into the spinal canal, the brain, or the nerve t runks were recently added. In the lat ter cases, the injections are carried out rather to demonstrate their localized effect than to cause a general systemic infection or intoxication. Intramuscular injection, however, as far as we know, was never yet employed, at least not consciously, as a method of introducing infectious or toxic products into the circulation. In therapeutics, however, we now and then come across the pract.ice of intramuscular administrat ion of drugs. I t originated in the t rea tment of syphilis with mercury. When at the beginning of the '8o's of the last century it was found tha t hypodermic injections of any compound of mercury gave considerable pain and favored the development of abscesses at the site of injection, the method developed of giving deep-seated injections,