Extractum Rhei. U. S., Br. Extract of Rhubarb.
Ext. Rhei [Powdered Extract of Rhubarb]
Related entries: Rheum
"One gramme of the Extract represents two grammes of rhubarb." U. S.
Extractum Rhei Alcoholicum; Extrait de Rhubarbe, Fr. Cod.; Extractum Rhei, P. G.; Rhabarberextrakt, G.; Estratto di rabarbaro acquoao. It.; Extracto acuoso de ruibarbo, Sp.
"Rhubarb, in No. 40 powder, one thousand grammes [or 35 ounces av., 120 grains]; Magnesium Oxide, fifty grammes [or 1 ounce av., 334 grains]; Starch, dried at 100° C. (212° F.), Alcohol, Water, each, a sufficient quantity to make five hundred grammes [or 17 ounces av., 279 grains]. Moisten the drug -with sufficient of a mixture of four volumes of alcohol and one volume of water, pack it in a cylindrical percolator and add enough of this 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 forty-eight hours. Then allow the percolation to proceed slowly, gradually adding menstruum of the same proportion of alcohol and water as before until the drug is exhausted. Recover the alcohol from the percolate by distillation at as low a temperature as practicable, and continue distillation until a residue of syrupy consistence remains in the still. Transfer this to a shallow dish, rinse the still with a little warm menstruum, add the rinsings to the residue in the dish, and evaporate the mixture to dryness, with frequent stirring, at a temperature not exceeding 70° C. (158° F.). Weigh the dry extract and add the magnesium oxide and sufficient of the dried starch to make the product weigh five hundred grammes [or 17 ounces av., 279 grains]. Reduce the mixture to a fine powder, mix thoroughly, pass the Extract through a fine sieve, transfer it to small, wide-mouthed bottles and stopper them tightly." U. S.
"Exhaust Rhubarb, in No. 20 powder, with Alcohol (60 per cent.) by the percolation process. Recover most of the alcohol from the percolate by distillation, and evaporate the residual liquid to dryness." Br.
The British extract (1914) is now nearly identical with the U. S. preparation; the menstruum used for the former is, however, slightly more aqueous. Rhubarb yields all its active matter to water and alcohol; but, unless the evaporation be performed with great care and with a moderate heat, it is certain that the purgative principle is to a greater or less extent injured or dissipated in the process, and the extract may thus become even less efficient than the root. When properly prepared, the extract has decidedly the peculiar odor of rhubarb. Dose, from two to ten grains (0.13-0.65 Gm.).