Tinctura Cantharidis (U. S. P.)—Tincture of Cantharides.
Related entry: Cantharis (U. S. P.)—Cantharides
(Modern shorthand: 1:20 91 %)
SYNONYM: Tincture of Spanish flies.
Preparation.—"Cantharides, in No. 60 powder, fifty grammes (50 Gin.) [1 oz av., 334 grs.]; alcohol, a sufficient quantity to make one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏]. Moisten the powder with thirty cubic centimeters (30 Cc.) [1 fl℥, 7♏] of alcohol, and pack it firmly in a cylindrical percolator; then gradually pour alcohol upon it, until one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏] of tincture are obtained"—(U. S. P.). This tincture has a green-yellow color. When prepared with diluted alcohol, the color is brownish-yellow, and the tincture deposits a precipitate. It possesses the characteristic odor of cantharides and a pungent taste.
Action, Medical Uses, and Dosage.—This is the best form for the administration of cantharides, in chronic gonorrhoea, gleet, amenorrhoea, and some urinary derangements. Externally, it is sometimes used as a rubefacient, but care should be taken to avoid its vesicating action. The dose is from 1 to 20 drops, every 3 or 4 hours.