IV.—The Pharmacological Action of Harmine

The seeds of Peganum Harmala contain two alkaloids, Harmaline and Harmine. The pharmacological actions of the former alkaloid have been described in a previous communication to this Society; in this paper an account is given of the pharmacology of the second alkaloid, Harmine. Harmine (C13H12N2O) was discovered by Fritche in 1847. Apart from a few observations by Tappeiner, its pharmacology has not been investigated. Tappeiner states that, in mammals at least, the general nature of poisoning by harmine is qualitatively the same as by harmaline, but that the former alkaloid is weaker in action. He found that a dose of 0·2 gramme per kilo of harmine is fatal to the guinea-pig in about 12 hours, while the same dose is fatal to the rabbit in about 1 hour, and that a frog is killed in about 7 hours by a dose of 0·03 gramme (per kilo?). He states further that there appears to be one qualitative difference between the actions of the two alkaloids, in that harmine produces paralysis of reflex excitability before arrest of the heart. It may be stated here that this does not constitute a qualitative difference between the actions of harmaline and harmine, because the same effect is produced by harmaline.