Emplastrum Resinae. U. S., Br.

Botanical name: 

Emplastrum Resinae. U. S., Br.

Rosin Plaster. Emp. Res. [Rosin Adhesive Plaster, Adhesive Plaster]

Related entries: Rosin

Resin Plaster, Br.; Emplatre Adhesif. Emplatre Resineux, Fr.; Emplastrum adhaesivum, P. G.; Heftpflaster, G.; Emplastro adesivo, It.

"Rosin, in fine powder, one hundred and forty grammes [or 4 ounces av., 411 grains]; Lead Plaster, eight hundred grammes [or 28 ounces av., 96 grains]; Yellow Wax, sixty grammes [or 2 ounces av., 51 grains], to make one thousand grammes [or 35 ounces av., 120 grains]. Melt the lead plaster and yellow wax together with a gentle heat, then add the rosin and, when melted, mix thoroughly, strain, and allow the product to cool, stirring until it stiffens." U. S.

"Resin, 100 grammes; Lead Plaster, 850 grammes; Hard Soap, 50 grammes. Melt each ingredient separately at as low a temperature as possible; mix." Br.

The name of this plaster was changed in the U. S. P. IX to rosin plaster, it was formerly termed adhesive plaster. It differs from lead plaster in being more adhesive and somewhat more stimulating. It resembles the common adhesive plaster of commerce, and is much employed for retaining the sides of wounds in contact, and for dressing ulcers according to the method of Baynton, by which the edges are drawn towards each other and a firm support is given to the granulations. The U. S. P. IX formula differs from that official in U. S. P. VIII in that the use of rubber and petrolatum in place of yellow wax and rosin was abandoned and the old process has been restored. As prepared by the Dublin College it contained soap, which gave it greater pliability, and rendered it less liable to crack in cold weather, without impairing its adhesiveness, and the process of that College has been adopted in the British Pharmacopoeia. It is usually spread upon muslin, and the spreading is best accomplished, on a large scale, by means of a machine, as described in the general observations upon plasters. It is kept ready spread by the pharmacist; but, as the plaster becomes less adhesive by long exposure to the air, the supply should be frequently renewed. Adhesive plaster originally employed by Baynton contained only six drachms of rosin to the pound of lead plaster. To obviate the possibility of irritating the skin, Herpin recommends the addition of lead tannate, the proportion of which, when adhesiveness is required in the plaster, should not exceed one-twentieth, but under other circumstances may be increased to one-twelfth.

The addition of Burgundy pitch or turpentine is objectionable, as they greatly increase the liability of the plaster to irritate the skin, and thus materially interfere with the purposes for which the preparation was chiefly intended.

The most popular and widely used forms of adhesive plaster used at the present time are those containing zinc oxide as one of the constituents.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.