Emplastrum Picis Cantharidatum (U. S. P.)—Cantharidal Pitch Plaster.
Related entry: Cantharis (U. S. P.)—Cantharides
SYNONYMS: Warming plaster, Warm plaster.
Preparation.—"Cerate of cantharides, eighty grammes (80 Gm.) [2 ozs. av., 360 grs.]; burgundy pitch, a sufficient quantity to make one thousand grammes (1000 Gm.) [2 lbs. av., 3 ozs., 120 grs.]. Melt the cerate of cantharides on a water-bath containing boiling water, and continue the heat for 15 minutes; then strain it through a piece of muslin of close texture so that the cantharides will be retained on the muslin. To the strained liquid add a sufficient quantity of burgundy pitch to make the whole weigh one thousand grammes (1000 Gm.) [2 lbs. av., 3 ozs., 120 grs.]; render the mixture homogeneous by stirring, remove the heat, and stir the mass until it thickens on cooling"—(U. S. P.).
It is necessary that the cantharides be in very fine powder. The direction to strain the cerate through muslin is very essential, that none of the particles of cantharides of any considerable size may come in contact with the skin and vesicate it.
Action and Medical Uses.—This plaster is a mild counter-irritant, and is considered useful in chronic articular diseases, chronic rheumatism, and such chest diseases as chronic bronchitis, chronic pleurisy, and in pulmonary engorgement of tubercular character. Also applied in phthisis, asthma, whooping-cough, bronchial catarrh, hepatitis, etc.