A COMPARATIVE STUDY OF SYNTHETIC AND NATURAL EPHEDRINES

¹ From the Department of Pharmacology, Johns Hopkins University

1. Synthetic ephedrine possesses qualitatively all the characteristics of natural ephedrine: its pressor action in experimental animals following an intravenous injection and much less constandly in men after oral administration, its oxytocic action on the isolated virgin guinea pig's uterus, its bronchodilating action after arecoline or physostigmine, its mydriatic action in rabbits and in men (definite in Caucasians but insignificant in colored races), its hyperglycemic action, and its detoxifying action in acute morphine poisoning.

2. Quantitatively, synthetic and natural ephedrines, in the form of the hydrochloride, injected intravenously, both have a M.L.D. of 60 mgm. per kilogram in white rabbits. The average ratio of the intensity of pressor action of synthetic ephedrine to that of natural ephedrine with optimal doses compared indirectly in pithed cats against epinephrine, is 1:1.33. The average ratio of the mydriatic action of synthetic ephedrine to that of natural ephedrine in Caucasians measured by the increase in the transverse diameter of the pupil, is 1:1.29.

3. Clinically, synthetic ephedrine on local application contracts the congested nasal mucous membranes and hypertrophied turbinates not unlike the action of natural ephedrine. In the treatment of bronchial asthma, synthetic ephedrine appears to have in some cases an antispasmodic but weaker action than natural ephedrine.

The Abbott Laboratories, Chicago, Illinois, also courteously supplied to the author a sample of synthetic ephedrine. Their product is optically inactive, melts at 190°C, and gives with cupric hydroxide a purplish color extractable by ether. It has a pressor action in experimental animals, and shows a decrease in response of pressor action on repeated injections. No extensive work on this product was done in connection with the present investigation. One would expect, however, that it should have the same pharmacological action if it is chemically identical with synthetic ephedrine.

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