Cantharis. Cantharides. Cantharis vesicatoria, Lytta vesicatoria; the Blister Beetle, or Spanish Fly; collected in Russia, Sicily, and Hungary.

Description. The insect is from 8 to 10 lines long; the elytra or wing-sheaths are long, of a fine green colour, and encase two thin brownish membranous wings. The flies swarm upon the trees about May or June, especially on the ash, lilac, and privet; and are brushed off by persons carefully masked, and received into linen cloths; they are killed by plunging into boiling vinegar, and then dried.

Prop. & Comp. The beetles have a peculiar urinous disagreeable odour, and a burning taste; the powder is a grayish brown, containing shining green particles; it should be free from mites. In addition to oily and fatty matters, the beetles contain a crystal-lizable principle, Cantharidine, to which their active properties are due. Cantharidine is insoluble in water, nearly so in cold alcohol, but more soluble in ether, chloroform, and strong acetic acid; as the active properties of the insect are partially yielded to warm and cold alcohol, it would appear that the cantharidine exists in the beetle as a somewhat soluble compound. From 1,000 parts of the flies, about four parts of pure cantharidine have been procured; catharidine has the formula (C10 H6 O4); it may be sublimed without injury; it has very powerful vesicating properties.

Off. Prep. Emplasteum Canthapjdis. Cantharides Plaster. (Cantharides, in very fine powder, twelve ounces; yellow wax, seven ounces and a half; prepared suet, seven ounces and a half; resin, three ounces; prepared lard, six ounces.)

Emplasteum Calefaciens. Warm Plaster. (Cantharides in coarse powder, four ounces; boiling water, twenty fluid ounces; expressed oil of nutmeg, four ounces; yellow wax, four ounces; resin, four ounces; soap plaster, three pounds and a quarter; resin plaster, two pounds.)

Linimentum Cantharidis. Cantharides, in powder, eight ounces; acetic acid, four fluid ounces; ether, twenty fluid ounces. Prepared by maceration and percolation.) [Cantharides, in fine powder, a troy ounce; oil of turpentine, half a pint. Prepared by maceration and percolation. U. S.]

[Ceratum Cantharidis. Cerate of Cantharides. Blistering Cerate. Cantharides, in very fine powder, twelve troy ounces; yellow wax, resin, each, seven troy ounces; lard, ten troy ounces. U. S.]

Tinctura Cantharidis. Tincture of Cantharides. (Cantharides, in coarse powder, a quarter of an ounce; proof spirit, twenty fluid ounces. Prepared by maceration and percolation.) [Two pints of tincture are obtained by percolating a troy ounce of cantharides in fine powder with diluted alcohol. U. S.]

Unguentum Cantharidis. Ointment of Cantharides. [Not officinal in U. S. P.] (Cantharides one ounce; yellow wax, one ounce; olive oil, six fluid ounces.)

Acetum Cantharidis. Vinegar of Cantharides. London Ph., 1851. (Spanish flies, reduced to the finest powder, two ounces; acetic acid, one pint. Macerate for eight days with the acid, frequently shaking them; then press and strain.)

Therapeutics. Cantharides, when applied externally, produce at first rubefacient and irritant effects, followed, if the preparation is strong, or long continued, by vesication; not unfrequently the active principle becomes absorbed, and the symptoms resulting from its internal administration then ensue. When taken internally in medicinal doses, the first indication is generally some diuresis, with a slight sensation referred to the neck of the bladder; and if the urine be then examined, it usually gives an indication of a trace of albumen; sometimes also a few blood disks are discovered by the microscope: when continued beyond this, strangury and bloody urine are produced, with priapism, sometimes aphrodisiac effects, and diminution or suppression of urine and its sequences, convulsions and death; the spinal cord is supposed to be influenced by cantharides.

Externally the Spanish fly is often used as a rubefacient in the form of a liniment, made with the tincture or acetum cantharidis, in cases where rubefacients in general are indicated; it has the advantage of acting slowly and for a longer period, and being less irritating to the patient, than strong ammoniacal or acetic acid embrocations: as a vesicant, its employment is very general, more so than that of any other agent; it forms the basis of the common blister, or emplastrum cantliaridis, of liniment of cantharides, and of other non-officinal blistering applications, as the vinegar of cantharides, etc.; the ointment is used to keep open blistered surfaces. These applications are useful over inflamed deep-seated parts, as in pleuritis, pericarditis, pneumonia, and other internal inflammations, after the more active febrile symptoms have been subdued by depletion and antiphlogistic remedies; and to diseased and painful joints. Vesication is also made use of on account of its revulsive action in internal congestions, as of the head, etc.; and over painful parts unattended with inflammatory action, as in various neuralgic affections; and lastly, in diseased conditions of the skin itself.

Internally the tincture of cantharides is given in chronic affections of the nervous system, especially of the spinal cord, as in chronic forms of paraplegia and in incontinence of the urine from want of tone in the bladder; occasionally it has been found useful in some non-inflammatory forms of albuminura, and in hydrocephalus; also in skin affections, especially in those of a squamous character; probably its diuretic action may be the cause of its value in the latter class of diseases. Sometimes it has been given in gleet and other mucous discharges.

Precautions to be used in the application and administration of Cantharides.

When the kidneys are acutely affected, the use of the Spanish fly, externally or internally, should be avoided, as the canthari-dine is. apt to become absorbed; in young or very debilitated subjects vesication by this agent should be cautiously produced, as sloughing may ensue and prove troublesome and even dangerous: placing a piece of tissue-paper over the surface and removing the blistering application before vesication has been fully induced, and the subsequent application of a poultice will often prevent the occurrence of strangury, and, at the same time, too great injury to the skin; vesication will generally ensue after the poultice has been applied. Many substitutes for the ordinary-blistering plaster have been proposed, such as the tela vesicatoria and blistering papers made by mixing an etherial or oily solution of cantharides with wax and fatty matters, and spreading the compound thinly on cloth or tissue-paper; also blistering liquids prepared by dissolving caniharidine in acetic acid and ether, or chloroform: the liniment of the Pharmacopoeia, which the author has extensively employed, vesicates with much certainty; it should, however, be used somewhat cautiously. These liquid applications are more efficient than the acetum cantharidis, as blistering agents, but the latter may be used as a rubefacient.

Dose. Of tinctura cantharidis, 5 min. to 30 min.

Adulteration. A beetle called the golden beetle has been found mixed with cantharides, and occasionally artificial glass tubes or beads coloured to imitate the Spanish fly have been added to increase the weight. It has been also asserted that flies deprived of their virtues by ether have been sold as genuine, and that euphorbium resin has been employed as an adulteration to powdered cantharides.

« Several other coleopterous insects, as Mylabris chicorii, etc, possess vesicating powers, and have been used in other countries as blistering agents.