Chinese Journal of Physiology

Chinese Journal of Physiology, 1929, Vol, III, No, 1, pp. 81—94.

COMPARATIVE STUDIES OF EPHEDRINE, RACEMIC EPHEDRINE AND PSEUDOEPHEDRINE

II. COMPARATIVE TOXICITY

C. PAK anv B. E. READ (From the Department of Pharmacology, Peking Union Medical College, Peping) Received for publication Nov. 8, 1928

In our previous communication (10) we showed qualitative and quantitative differences in the action of ephedrine, ephetonin and pseudoephedrine. Curtis (5) in showing that ephedrine is more active than ephetonin found that the difference was not so pronounced for minute doses of these drugs. Whereas 0.05 mg per kilogram bodyweight in cats showed little difference, 4 mg produced very divergent effects. He explains Kreitmair’s (7) original claim for identical quantitative effects by the small dosage used. Berger (2) in summarizing extensive clinical studies upon ephedrine and ephetonin considered ephetonin less toxic than ephedrine stating that in cases of heightened sympathetic irritability the possible by-effects, ‘‘are incomparably more frequent and more pronounced with ephedrine than with ephetonin”. Certain by-effects related to the neurotropic action of ephedrine can be so considered, but in view of the greater musculotropic effect of ephetonin it is quite logical that Berger should have observed with ephetonin cardiac palpitations and untoward effects of muscular origin. This and other general evidence shows that there is a qualitative difference in action, a quantitative difference in effect, and differences in the minor toxic effects of these two isomers. There remains the question of absolute and relative toxicity from the lethal standpoint.

A study of the comparative action and toxicity of ephedrine and pseudoephedrine has been made by Fujii (6). He concluded that for the frog pseudoephedrine was less toxic in the proportion of I to 1.6, but for the mouse ephedrine had a larger lethal dose in the proportion of 1 to 0.8 toxicity for. pseudoephedrine and ephedrine respectively.