Extractum Rhei (U. S. P)—Extract of Rhubarb.
Related entry: Rheum (U. S. P.)—Rhubarb
Preparation.—"Rhubarb, in No. 30 powder, one thousand grammes (1000 Gm.) [2 lbs. av., 3 ozs., 120 grs.]; alcohol, water, each, a sufficient quantity. Mix eight hundred cubic centimeters (800 Cc.) [27 fl℥, 25♏︎] of alcohol with two hundred cubic centimeters (200 Cc.) [6 fl℥, 366♏︎] of water, and, having moistened the powder with four hundred cubic centimeters (400 Cc.) [13 fl℥, 252♏︎] of the mixture, pack it firmly in a conical percolator; then add enough menstruum to saturate the powder and leave a stratum above it. When the liquid begins to drop from the percolator, close the lower orifice, and, having closely covered the percolator, macerate for 48 hours. Then allow the percolation to proceed, gradually adding menstruum, using the same proportions of alcohol and water as before, until the tincture passes nearly tasteless. Reserve the first one thousand cubic centimeters (1000 Cc.) [33 fl℥, 391♏︎] of the percolate, and set it aside in a warm place, until it is reduced by spontaneous evaporation to five hundred cubic centimeters (500 Cc.) [16 fl℥, 435♏︎]. Evaporate the remainder of the percolate, in a porcelain vessel, by means of a water-bath, at a temperature not exceeding 70° C. (158° F.), to the consistence of syrup. Mix this with the reserved portion, and continue the evaporation, at or below the before-mentioned temperature, until the mixture is reduced to a pilular consistence"—(U. S. P.).
Description, Medical Uses, and Dosage.—(See Rheum). Great care is required in the preparation of this extract, as both the tonic and purgative properties of rhubarb are very apt to become deteriorated by the process. Only a gentle heat must be employed. The extract prepared by evaporation in vacuo, will be found decidedly the best; it possesses the odor and taste of the root. Extract of rhubarb, only when well and carefully prepared, possesses virtues similar to the drug itself, and may be given in pill form, or in solution in doses of from 5 grains to ½ drachm.
