THE EFFECT OF SITES AND ROUTES OF ADMINISTERATION OF SOME DRUGS ON ITS LD₅₀IN ANIMALS

In mice when procaine hydrochloride and atropine sulphate were administered into the deep part of the wrist at median line (the so called "median wrist"), the LD₅₀ of these drugs were significantly lower than those when the drugs were injected intramuscularly into the hind legs or subcutaneously at the back. The toxicity of potassium cyanide for mice and rats by "median wrist" injection was significantly lower than that by intramuscular or subcutaneous injections. The cause of these differences was mainly not due to variable absorptions of the drugs from the injected sites. The effects of sites and routes of administeration on the toxicity of sodium nitrite were not statistically significant. The toxicity of potassium cyanide for rats by "median wrist" injection was lowered, if the brachial plexus of the injected side was resected a week earlier; this implies that the toxicity of the cyanide is related to the nervous functions. The results revealed that procaine hydrochloride given by "median wrist" injection was as effective as sodium nitrite by the same route in relieving potassium cyanide poisoning in mice, while procaine hydrochloride given by intramuscular injection was inferior to intramuscular injection of sodium nitrite.