Ointment of Canthar′ides. Syn. Unguentum cantharidis (B. P., Ph. L., D., & U. S.), U. lyttæ, L. Prep. 1. (Ph. L.) Cantharides (in very fine powder), 3 oz.; distilled water, 12 fl. oz.; mix, boil to one half, to the strained liquid add of resin cerate, 1 lb., and evaporate to a proper consistence.
2. (Ph. D.) Liniment of Spanish flies, 8 fl. oz.; white wax, 3 oz.; spermaceti, 1 oz.; melt together with a gentle heat, and stir until it concretes.
3. (Ph. E.)—a. Unguentum infusui cantharidis—Ph. E. Powdered Cantharides
1 oz.; boiling water, 1⁄4 pint; infuse one night (12 hours), strain with expression, add of lard 2 oz., and boil until the water is expelled; then add beeswax and resin, of each 1 oz., and when these are liquefied, remove the vessel from the fire, and further add of Venice turpentine, 2 oz.
b. (Unguentum pulveris cantharidis—Ph. E.) Resin ointment, 7 oz.; melt, add of cantharides (in fine powder), 1 oz., and stir until the whole is nearly cold.
4. (B. P.) Cantharides, in fine powder, 1; olive oil, 6; yellow wax, 1; digest the cantharides in the oil for 12 hours, and for 1⁄4 hour at 212°; strain, add the melted wax, and stir till cold.
Obs. The above preparations are frequently called ‘blister ointment’ or ‘epispastic ointment.’ They are used to keep blisters open after they have been produced by stronger compounds. The first three compounds are regarded as milder than the last (3, b), which contains the flies in substance. The P. Cod. contains an ointment (UNG. EPISPASTICUM FLAVUM) which is weaker than the above, prepared by digesting the bruised flies in lard, for 3 hours, over a warm bath; about 1⁄6th part of wax is next added to the strained fat, which is then coloured with turmeric, and scented with oil of lemon. See Cerate, Pommade, Vesicants, and below.
Ointment of Cantharides, Extract of. (M. Cap.) Syn. Unguentum cum extracto cantharidis. Prep. Alcoholic extract of cantharides, 8 gr.; oil of roses, 1 dr.; beef marrow, 2 oz.; oil of lemon, 40 minims. To promote the growth of the hair.
Ointment of Cantharides with Mercury. Syn. Unguentum cantharidis cum hydrargyro. Prep. Lard, 65 parts; Spanish flies, 29 parts; strong mercurial ointment, 6 parts. Mix. Used in Normandy to indolent tumours.
Ointment of Canthar′idine. Syn. Unguentum cantharidinæ, L. Prep. (Soubeiran.) Cantharidine, 1 gr.; white wax, 1 dr.; lard, 7 dr.; mix thoroughly. (See above.)