CA NTHARIDINE. or cantharidal cam phor, is found in glistening rectangular prisms, which melt at 21S°; heated higher it gives off a heavy, white, very irritating vapor, condensing unaltered to crystals. It is easily soluble in acetone, sulphuric acid, and glacial acetic acid, less so in chloroform (1 to SO), very little in 90-per-cent. alcohol, 1 to 500 in pe troleum ether, and 1 to 5000 in water; the aqueous solution, though practically tasteless, is by no means devoid of vesica tory power even in the minutest quanti ties. Cantharidine is also soluble in fatty oils and gives an acid reaction to very sensitive litmus-paper; it volatilizes at 100°. It likewise combines readily with alkalies to form soluble salts. If nitric acid is added to cantharidinate of sodium, crystals of cantharidine are at once precipitated.
The foregoing paragraph sufficiently explains the formation of cantharidate of potassium, which, however, seems only to have had an ephemeral existence.
Cantharidath of cocaine is a mixture of cantharidate of sodium and cocaine muriate, and occurs as a white, inodor ous, amorphous powder with a sharp taste, readily soluble in alcohol, ether, petroleum spirit, and hot water. Its uses are the same as those of the potas sium salt.
Physiological Action.—All species of cantharides are powerfully irritant when applied to the skin, and likewise vesi cant, these two properties depending upon the cantharidine. Internally the drug can be given properly only in the form of tincture, for obvious reasons (see PoIsoNING), though the powder is sometimes, though rarely, mistakenly employed; and even the tincture should be employed only in connection with copious diluents and demulcents. Suit ably administered, the tincture is a stim ulant diuretic, and it appears also to ex ert a specilic influence upon the mucous membrane of the genito-urinary sys tem, particularly the neck of the bladder. In larger doses it is highly irritant, and it is not an uncommon accident for suf ficient of the drug to be absorbed during applications to the skin to cause great irritation of the kidneys, as evidenced by painful micturition and bloody urine.
The inflammation produced by can tharides begins in the glomeruli and not in the straight tubes. The first condi tion of the kidneys noticed after the administration of the drug is extravasa tion of leucocytes into the glomeruli and an exudation of a fibrous matrix.
This is followed by filling of the glom eruli and the proximate tubules with a granular fluid, after which comes swell ing of the cells of the capsule. Next in order swelling of the cells of the collecting tubes and of the whole uri nary tubule is observed; and in the last stage multiplication of the cells of the straight collecting tubes which are thrown off so that their lumen becomes filled with exuded cells. Murrell, Loud. ("Manual of Mat. Med. and Therap.," '96).
Lahousse finds that cantharides affects simultaneously the Malpighian bodies, the renal tubules, and the matrix of the kidney. The Malpighian vessels are greatly congested; albumin, leucocytes, and a few red corpuscles escape; the epithelium covering the vessels lining the capsule swell and desquamate; the endothelium of the vessels swells and may choke their lumen, the tubule-cells swell, become granular, and die. The tubules contain hmmoglobin in the form of brilliant-red homogeneous cylinders. Leueocytes escape into the matrix. Other observers hold that the Mal pighian bodies are alone, or chiefly, affected. Ringer and Sainsbury ("Hand book of Therap.," '97).
Cantharidal Poisoning.—The drug in non-medicinal doses is an acrid, corrod ing poison, the chief symptoms being a burning sensation in the throat, violent pains in stomach and bowels, nausea, vomiting, and purging,—the dejections being frequently bloody and purulent,— great heat and irritation of the urinary organs, sometimes accompanied by pain ful erethism, and in the male painful priapism, quick and hard pulse, labo rious breathing, convulsions, tetanus, delirium, and syncope. The morbid ap pearances are principally inflammation and erosion of the stomach. If the flies or powder have been ingested, character istic debris will be found adhering to the mucous coat of the stomach and in testines, and, if recent, mixed with the contents of the prima vice generally; powder of cantharides has been identi fied in the stomach nine months after death; there are also discoverable the marks of violent inflammation through out the urinary organs; but such are usually most prominent when the poi soning is not fatal. The kidneys are frequently gorged with blood, as is the brain.