Cantharis Vesicatoria. Cantharides. The Blister Beetle or Spanish Fly. A Coleopterous Insect, formerly known as Lytta, and Meloe Vesicatoria. It is collected in Russia, Sicily, and Hungary, and is also found in France, Germany, and other parts of Europe. It has its representatives in various parts of the world: thus the Mylabris Cichorii (vern telini) occurs in Syria and throughout the East; the Mylabris TrianthemAe and Lytta Gigas occur in Senegal; the Lytta Vittata in America; and the Lytta Ruficeps in Chili.
* Op. cit.
Christison, op. cit.
Med. Prop. and Action. All the above species of Cantharis, Mylabris, and Meloe, when applied to the skin, are powerful irritants and vesicants; their irritant property depending upon the presence of an acrid crystallizable principle, Cantharidine, which is common to the whole family. Their value as external applications is considered in the article Blisters, part ii. Cantharidine is soluble in ether, strongacetic acid, and chloroform, and is the active ingredient in the various blistering fluids and blistering tissues which are used as substitutes for the ordinary blister plaster. Internally, Cantharides is only employed in the form of tincture, in doses of ex. cautiously increased to exxx. daily, with the copious use of diluents and demidcents. Thus given, it is a stimulant diuretic, and appears to exercise a peculiar action over the mucous membrane of the genito-urinary system, and particularly on the neck of the bladder. From a series of carefully conducted experiments on twenty-two subjects, students, Dr. Giacomini* draws the conclusion that Cantharides is a powerful depressant, contra-stimulant, and antiphlogistic, and that it may be advantageously employed as such in acute inflammations. In every case (twenty-two) he found a remarkable diminution in the force and frequency of the pulse, and a great depression of the vital powers. Its antiphlogistic powers have been also tested by Borda, Rasori, and Larber. Cantharidine being rapidly soluble in oil, it is injudicious and unsafe to administer oleaginous substances at the same time as Cantharides, as the active principle may thus become freed, and, being absorbed into the system, may produce poisonous effects. In large or poisonous doses, it causes a burning pain in the throat and pit of the stomach, extending at length over the whole abdomen: excessive pain in swallowing; dryness of the fauces; copious discharge of blood or bloody mucus from the stomach, and in less quantity from the bowels; tenesmus; distressing strangury; bloody urine; priapism; and inflammation of the genital organs. The patient is restless, the breathing laborious, the pulse quick and hard; headache, delirium, and convulsions are sometimes superadded.
Offlc. Prep. 1. Emplastrum Cantharidis (Cantharides in fine powder oz. xij.; Yellow Wax oz. viiss.; Prepared Suet oz. viijss.; Resin oz. iij.; Prepared Lard oz. vj.).
2. Emplastrum Calefaciens (composed of a Watery Infusion of Cantharides, Oil of Nutmeg, Yellow Wax, Resin, Soap Plaster, and Resin Plaster). Rubefacient and stimulant.