Chinese Journal of Physiology

82 C. PAK anp B, E, READ

These results leave the question of the relative toxicity of these two substances in a somewhat indefinite position. So we have taken a much larger variety of animals, frogs, hamsters, rats, gray and white rabbits, and dogs to determine this point, at the same time we have made a comparison with racemic ephedrine, referred to as ephetonin, and we have made a careful study of the toxicity of pseudoephedrine.

A comparison of the toxicity of ephedrine and ephetonin was made by Kreitmair (7). He used white mice and obtained identical results, Chen (8) confirmed this conclusion by a series of rabbit experiments in which he obtained a minimum lethal dose for both isomers of 60 mg per kilogram by intravenous injection. We have-not repeated Kreitmair’s work because Fujii’s results show how differently from other animals mice react to the ephedrines. Our results with hamsters, a kind of field mice, are similar in showing a relative effect different from any of the other animals used. In white rabbits Chen’s minimum lethal dose (3,4) for ephedrine does not agree with that reported by Nagel (9), or Kreitmair (7), both of whom gave 50 mg.

The minimum lethal dose of ephedrine has been reported upon by various workers. Miura (8) in the original work upon its toxicty used frogs, rabbits (subcutaneously), and dogs (subcutaneously), and gave his results as 400 to 500, 300 to 460, and 220 mg respectively. Amatsu and Kubota (1) obtained the same result with frogs, Fujii found the higher figure to be true for his animals, which may have been a different species of Rana. Kreitmair (7) and. Chen (4) both reported larger values, which we are inclined to believe are due to salts not entirely free from isomers. It is well known that different species have been used. In conducting our experiments we at first found considerable variation in result, which was later corrected by improved technique. These points emphasize the need for results obtained from identical species of animals, the same purity of the isomers, and similar technique. Fair comparative values are hard to make by comparing results obtained in different laboratories, with varying species of animals, and by a technique that may be not quite the same, e.g., there is too big a difference in the cat intravenously as observed by Kreitmair (7) and Chen (4), 60 and 75 mg respectively, for a good comparison to be made with these figures and that possibly obtained by a third worker upon ephetonin or pseudoephedrine.

Most work has been done with white rabbits, Fujii’s (6) experiments confirmed Miura’s (8) earlier results obtained by subcutaneous