Glyceritum Picis.—Glycerite of Tar.
Related entry: Pix Liquida (U. S. P.)—Tar
SYNONYMS: Glycerin of tar, Glycerole of tar.
Preparation.—Take of tar, 1 troy ounce; glycerite of starch, 8 troy ounces. Transfer the tar to a mortar, and gradually add the glycerite of starch, stirring constantly until an even mixture results (New Remedies, 1879, p. 200). It is advisable to previously warm the glycerite of starch.
Action and Medical Uses.—This preparation forms a very useful local application in lichen, prurigo, pityriasis, psoriasis, lepra, herpes, erythema, eczema, tinea, pruritis, and alopecia; also in indolent and gangrenous ulcers. It may be rubbed upon the affected part, or be spread on a piece of linen and thus applied. It is very apt to afford more or less relief, even when it does not remove the disease. Do not confound this valuable tar compound for external use with the following liquid to be taken internally:
Related Preparation.—GLYCERITUM PICIS LIQUIDAE. A good formula, with its uses, is as follows: Take of tar, strained, 1 troy ounce; carbonate of magnesium, rubbed to powder on a sieve, 3 troy ounces; alcohol, 2 fluid ounces; glycerin, 4 fluid ounces; water, a sufficient quantity. Mix the alcohol and glycerin with 10 fluid ounces of water. Rub the tar in a mortar with the carbonate of magnesium added gradually, until a smooth pulverulent mixture is obtained; then, add gradually, in small portions at a time, with thorough trituration continued for 15 or 20 minutes, 6 fluid ounces of the mixture of alcohol, glycerin, and water, and strain with strong pressure; return the residue to the mortar, and repeat the trituration as before, with 5 fluid ounces more of the same liquid, and again strain and express; again treat the dregs in the same manner with the remainder of the fluid mixture, and after expression, reduce the residue by trituration to a uniform condition, and finally pack firmly in a glass funnel, prepared for percolation, and pour upon it the expressed liquors, previously mixed, and when the mixture has all passed from the surface, continue the percolation with water until 1 pint of liquid has been obtained.
This is an elegant and palatable preparation of tar, of a beautiful rich reddish-brown color at first, but losing its transparency from a deposition of resinous matter, which does not, however, affect the medicinal virtues of the preparation in the least. If glycerin be substituted for the alcohol, in its preparation, the solution is nearly as strong as when alcohol is employed and deposits less resin. Glycerin appears to be a good solvent of the medicinal properties of tar, and possessing demulcent, alterative, and nutrient properties, serves as a valuable adjunct to the latter therapeutically.
Glycerin solution of tar is very valuable in chronic cough, chronic laryngeal, bronchial and pulmonary affections, and, being free from sugar, it is less liable to offend the stomach and disturb the digestive functions of patients requiring its long-continued use. It may be associated with the fluid extracts of wild cherry bark, blood-root, etc., to suit the views of the prescribing physician. The dose is from 2 to 4 fluid drachms, 3 or 4 times a day, which will represent from about 7 ½ to 15 grains of tar (J. B. Moore, Amer. Jour. Pharm., 1869, p. 115).