Abstract
Digitalis varies markedly in its pharmacological activity, even the alcoholic extracts deteriorating often within a comparatively short time. In view of the extreme differences of opinion held by pharmacologists and pharmacists in regard to the effect of ultraviolet rays on digitalis, the present investigation was undertaken. A standard tincture was kept in the ice-chest in the dark. Samples of this were irradiated with an Alpine Sun lamp, and with a water-cooled Kromayer lamp with and without various filters, and the pharmacological activity of the tinctures after assay was determined by 4 different methods: (1) the official one-hour frog method, 1 (2) the cat method of Hatcher and Brodie, 2 (3) the phytopharmacological method of Macht and Krantz, 3 and (4) the goldfish method of Pit-tenger and Vanderkleed. 4 The great majority of animal experiments were performed on cats because, in the author's experience, that is the most reliable method for assaying digitalis. About 100 cat experiments were performed in connection with the present investigation. Each sample or fraction of digitalis tincture was tested on at least 3 cats and in cases where the readings obtained showed a wide divergence, as many as 8 cats were sometimes used to obtain the average minimal lethal dose. The phytopharmacological method was found to be particularly adapted to comparative study of various samples of digitalis simultaneously and under identical conditions of light, temperature, barometric pressure, etc. At least one hundred sets of such experiments were performed and each control, as well as each sample of digitalis tincture, was tested on 8 or 10 healthy seedlings of Lupinus albus. The frog and goldfish methods were used only to corroborate the results obtained by the cat and phytopharmacological experiments. Each sample was tested on at least 10 goldfish and 12 frogs.
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