Unguentum Cantharidis.—Ointment of Cantharides.

Botanical name: 

Related entry: Cantharis (U. S. P.)—Cantharides

SYNONYMS: Ointment of Spanish flies, Unguentum irritans.

Preparation.—"Take of cantharides, yellow wax, of each, 1 ounce (av.); olive oil, 6 fluid ounces. Infuse the cantharides in the oil, in a covered vessel, for 12 hours; then place the vessel in boiling water for 15 minutes, strain through muslin with strong pressure, add the product to the wax previously melted, and stir constantly while the mixture cools"—(Br. Pharm., 1885). The British Pharmacopoeia (1898) directs cantharides 1 part, and benzoated lard 10 parts. Another formula is as follows:

Take of finely powdered Spanish flies, olive oil, each, 3 ounces; oil of turpentine, 1 ½ fluid ounces; yellow wax, resin, each, 2 ounces. Mix the flies, olive oil, and turpentine, place them in a vessel on a water-bath, and continue the heat until the turpentine has nearly evaporated, stirring the mixture occasionally. Then add the wax and resin previously melted together, and heat till the articles are thoroughly incorporated; remove from the bath and stir till cold (W. Procter, Jr.).

Action and Medical Uses.—This is used not for the purpose of causing vesication, but as a rubefacient stimulating dressing to blisters, to induce a continuation of the discharge, whenever such is desirable. It has also been applied in alopecia and muscular rheumatism.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.