There are also—An ointment; a blistering paper, Charta epispastica; a blistering plaster, Emplastrum cantharides; and a warm plaster, Emplastrum calefaciens.
§ 634. Fatal Dose.—It is difficult to state the fatal dose of cantharidin, the unassayed powder or tincture having mostly been taken. A young woman died from 1·62 grm. (25 grains) of the powder, which is perhaps equivalent to 6·4 mgrms. (1 grain) of cantharidin, whilst the smallest dose of the tincture known to have been fatal is (according to Taylor) an ounce. This would be generally equivalent to 15 mgrms. (·24 grain). Hence the fatal dose of cantharidin may be approximately stated as from 6 mgrms. upwards. But, on the other hand, recovery has taken place from very large doses.
§ 635. Effects on Animals.—Certain animals do not appear susceptible to the action of cantharidin. For example, hedgehogs and swallows are said to be able to take it with impunity. Radecki[639] found that cantharidin might even be injected into the blood of fowls without any injury, and frogs also seem to enjoy the same impunity; while dogs, cats, and other animals are sensitive to the poison. Galippe ascertained that after the injection of 5 mgrms. into the veins of a dog, there was exaltation of the sexual desire; the pupils quickly dilated, the dog sought a dark place, and became sleepy. Animals when poisoned die in asphyxia from paralysis of the respiratory centre. Schachowa[640] made some observations on the effect of cantharides on the renal excretion of a dog fed daily with 1 grm. in powder. On the third day, pus corpuscles were noticed; on the fifth, bacteria; on the thirteenth, the urine contained a large quantity of fatty matters, and several casts; and on the seventeenth, red shrivelled blood corpuscles were observed.
[639] Die Cantharidin Vergift., Diss., Dorpat, 1806.
[640] Unters. über die Nieren, Diss., Bern, 1877; Cornil, Gaz. Méd., 1880.
Effects on Man.—Heinrich[641] made the following experiments upon himself:—Thirty living blister-beetles were killed, and digested, without drying, in 35 grms. of alcohol for fourteen days, of this tincture ten drops were taken. There ensued immediately a feeling of warmth in the mouth and stomach, salivation, the pulse was more frequent than in health, there was a pleasant feeling of warmth about the body, and some sexual excitement lasting three hours. In half an hour there was abdominal pain, diarrhœa, and tenesmus, and frequent painful micturition. These symptoms subsided in a few hours, but there was a want of appetite, and pain about the kidneys lasting until the following day. In the second experiment, on taking 1 cgrm. of cantharidin, there were very serious symptoms of poisoning. Blisters formed on the tongue, and there was salivation, with great difficulty in swallowing, and a general feeling of illness. Seven hours after taking the poison, there were frequent micturitions of bloody urine, diarrhœa, and vomiting. Twenty hours after the ingestion the face was red, the skin hot, the pulse twenty beats beyond the normal pulsation, the tongue was denuded to two-thirds of its extent of its epithelium, and the lips and mucous membrane were red and swollen; there was great pain in the stomach, intestines, and in the neighbourhood of the kidneys, continuous desire to micturate, burning of the urethra, and swelling of the glands. There was no sexual excitement whatever; the urine was ammoniacal, and contained blood and pus; the symptoms gradually subsided, but recovery was not complete for fourteen days.
[641] Schroff, Zeitschrift d. Ges. d. Aerzte in Wien, 13, 56.