Cantharis Vesicatoria. Cantharides.
Cantharis. Class Insecta. Order Coleoptera, Linn. — Family Trachelides. Tribe Cantharides, Latreille.
Gen. Ch. Tarsi entire ; nails bifid ; head not produced into a rostrum ; elytra flexible, covering the whole abdomen, linear semicylindric ; wings perfect ; maxillae with two membranaceous lacinae, the external one acute within, subuncinate ; antennae longer than the head and thorax, rectilinear ; first joint largest, the second transverse, very short ; maxillary palpi larger at tip. — Say.
History. — There are a number of insects inhabiting various sections of the world which possess acrid properties, and which, when applied to the skin produce vesication ; the most common in use are those under present consideration, Spanish Flies, or Cantharides, the Cantharis Vesicatoria of Latreille, Meloë Vesicatorius of Linnaeus, or Lytta Vesicatoria, and Cantharis officinalis of other naturalists. At what period they were introduced into the practice of medicine is a matter of uncertainty. The Spanish fly is a native of Europe, and is imported into this country from Messina and St. Petersburg. Those from Russia are the best, and may be known by their greater size, and somewhat copper color. This insect may be distinguished from other analogous ones, by presenting two wing covers of a shining-green color, long and flexible, which cover two membranous wings of a brownish color ; the head is large and heart-shaped, having two thread-like, black, jointed antennae ; the thorax is short and quadrilateral, and along the head and chest is a longitudinal furrow. The fly is about six or ten lines long, and weighs about two grains and a half. They have a peculiar, disagreeable odor, and a faint resinous taste, followed by acridity. In the countries which they inhabit they are found on certain trees as the elder, plum, rose, white poplar, privet, elm, lilac, ash, and honeysuckle, the leaves of which serve them as food. In the state of larva, they inhabit the earth, and prey upon the roots of plants. In the months of May and June, they come forth in swarms in the form of flies, and fill those trees and shrubs which they prefer. At this season they are collected, which is attempted at dawn, when they are torpid from the cold of the night ; to undertake their removal in the day-time would be a serious measure. Those who gather them being protected with masks and gloves, shake them from the trees and receive them into sheets spread below ; they are then immersed in vinegar or exposed to the vapor of boiling vinegar, spirit, or turpentine, for the purpose of killing them, after which they are quickly dried in the sun, or in heated apartments, and when perfectly dried, are put into casks or boxes lined with paper, and closed so as to exclude as much as possible the atmospheric moisture. It abounds the most in Spain, Italy, Southern France, Southern Russia, Sicily, and is found to some extent in all the South of Europe and in Western Asia.
When dried the flies present the form and color above described, together with the disagreeble odor of the living insect, and an acrid, burning, and urinous taste. They are easily pulverized, the powder presenting a dirty grayish-brown color, interspersed with numerous shining-green particles, the fragments of the feet, head, and wing covers. And as these particles resist the process of putrefaction for a long time, they may consequently be detected in the stomach many months after death occurring from the internal administration of cantharides. When kept perfectly dry, and well closed, the vesicating property of the flies may be preserved for many years. Hence they should always be kept in well stoppered bottles, and powdered only as required. If purchased in powder they may have lost their activity, or suffered from adulteration with euphorbium, or some other insects. To preserve them from insects, various means have been advised, as the introduction of a few lumps of camphor into the vessel containing them, or the addition of carbonate of ammonia, or a few drops of strong acetic acid. Exposing them for half an hour in glass bottles, to the heat of boiling water, destroys the insects and eggs, without impairing the virtues of the flies; of course they must not be allowed to come in contact with the water. The properties of the fly are much diminished by the insects which feed upon them.
Cantharides powder yields its active properties to boiling water, acetic acid, alcohol, proof spirit, ether, the fixed and volatile oils. The active principle is a white, crystalline substance, termed Cantharidin, which is soluble in ether, acetic acid, fixed and volatile oils, and in alkaline solutions. It is in small, white, pearly prisms, which are neutral, insoluble in water and cold alcohol, but soluble in ether, alkaline solutions, acetic acid, the oils, and in boiling alcohol which deposits it upon cooling ; it fuses at 210°, volatilizes at a higher heat without decomposition, and evaporates slowly at atmospheric temperatures. It is said to exist principally in the trunk and soft parts of the body, and may be obtained by exhausting powdered cantharides with cold rectified spirit, by percolation, concentrating the tincture till most of the alcohol is expelled, and allowing the residue to rest for a long time until crystals form. It may be freed from impurities by elutriation with a little cold rectified spirit, which scarcely acts on crystallized cantharidin ; and it may be obtained quite pure by re-dissolving them in boiling rectified spirit, adding animal charcoal, and re-crystallizing them by rest and cooling. Ether is, however, preferred to alcohol in preparing these crystals, as it dissolves less of the green oil, which is very difficult to separate. The composition of cantharidin is carbon 61.68 per cent., hydrogen 6.04, and oxygen 32.28, or C10 H6 O4.
Cantharides are found to contain in addition to their active principle, a green oil, insoluble in water, soluble in alcohol, and inert as a vesicatory; a black matter, soluble in water, insoluble in alcohol, and inert; a yellow viscid matter, soluble in water and alcohol, and inert as a vesicant; a fatty matter insoluble in alcohol ; phosphates of lime and magnesia, acetic acid, etc. Although cantharidin is insoluble in water and cold alcohol, yet the decoction and tincture of cantharides possess the active properties of the insect, which is owing to the presence of the yellow matter combined with it. The best menstruum for cantharides is sulphuric ether, which dissolves only the active constituents.
Properties and Uses. — In large doses, narcotic and irritant ; in medicinal doses, stimulant and diuretic. In large doses, its use is dangerous, being attended often by violent inflammation of the alimentary canal and urinary organs, strangury, irritation of the sexual organs, in the female, abortion ; also, headache, delirium, convulsions and coma. Twenty-four grains of the powder or one ounce of the tincture have produced alarming symptoms. There is no known antidote to its poisonous effects, which must be treated on general principles. Medicinally, they are sometimes given in chronic gonorrhea, gleet, leucorrhea, seminal weakness, paralysis and chronic inflammation of the bladder. They have also been reputed useful in the anasarcous swellings succeeding scarlatina, diabetes, scaly cutaneous eruptions, chronic eczema, incontinence of urine, amenorrhea, etc. Thirty drops of solution of potassa, given every hour, is said to be an effectual remedy in cantharidal strangury. Dose, of powdered cantharides, half a grain to two grains. (See Tinctura Cantharidis.)
Externally, cantharides cause redness, vesication, suppuration or sloughing, according to the length of contact with the integuments. Their most general use is to produce vesication. Blisters are sometimes beneficial in tic-douloreux, sciatica, local chronic inflammations, diseases of the brain, chest and abdomen, to excite the languid action of vessels, in recession of exanthematous affections, and to rouse from general defective sensibility, as in typhoid fever. In their application to children, much care should be observed, especially in typhoid conditions, exanthema, and where a tendency to sloughing exists. A piece of white paper soaked with the Cantharidin, which is greenish and liquid, laid on the part, and covered with a compress, and confined by means of a bandage, will vesicate in three or four hours. A vesicating oil has been recommended by E. Dupuy, prepared as follows : To one part of pulverized cantharides add in a close vessel, a mixture of chloroform and castor oil of each, by weight, one and a half parts ; after some hours transfer the ingredients to a glass apparatus, and displace the liquid in the usual way ; it will amount to about two-thirds of the original bulk of the liquid employed. A few drops of this vesicating oil applied to the arm of an adult will produce a perfect blister in about eight hours. It is easy of application on any surface, holds the vesicating agent free from the disagreeable concomitants of the ordinary fly-blister, and retains the cantharidin in a soluble state. Its action will probably be favored by the use of oil-silk over the application of it to the skin.
Off. Prep. — Tinctura Cantharidis ; Emplastrum Cantharidis.