THE ESTIMATION OF DIGITALIS BY PIGEON-EMESIS AND OTHER METHODS

In a recent number of this JOURNAL, Hanzlik (1) has described a new method of estimating the potency of digitalis preparations in which the pigeon is used. The procedure is simple. An injec-tion of the diluted tincture of digitalis is made directly into a wing vein, and the pigeon is then watched for ten to fifteen min-utes to see whether it vomits. Hanzlik suggests that the potency of tinctures of digitalis be estimated by determining the minimal emetic dose, and says “In determining the minimum emetic dose, a series of pigeons is injected and the just effective dose determined, which is the just effective dose causing emesis in 2 out of 3 pigeons. ” Furthermore he says “Considerable experi-ence with the method in this laboathry during the past two years indicate that from 10 to 12 pigeons are use in the assay when starting with an unknown preparation. ” Finally Hanzlik suggests that “The minimum emetic dose.... might be called a pigeon-unit, following the expression of standards in vogue with insulin, pituitary, etc.” Since the correct estimation of digitalis is a problem ever present in this laboratory, I have investigated the proposed new method, with the more interest because, as described, it entirely disregards two principles of biological assay on the observance of which increasing reliance is being placed by many workers. In the first place it proposes the determination of a “minimal emetic dose. ” Now Trevan (2) showed three years ago that the expression “minimal lethal dose ” is probably never an accurate expression. Substances as dissimilar as cocaine and diphtheria toxin, when tested on mice, and digitalis, when tested on frogs