Resina Jalapae. U. S. (Br.) Resin of Jalap. Res. Jalap.
"Jalap Resin is a mixture of resins obtained from Jalap" Br.
Jalapae Resina, Br.; Resine de Jalap, Fr. Cod.; Jalapenharz, G.; Resina di gialappa. It.; Resina de jalapa, Sp.
"Jalap, in No. 60 powder, one thousand grammes [or 35 ounces av., 120 grains]; Alcohol, Water, each a sufficient quantity. Moisten the powder with five hundred mils [or 16 fluid-ounces, 435 minims] of alcohol, and pack it in a cylindrical percolator; then add enough alcohol 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 alcohol, until the percolate ceases to produce more than a slight turbidity when dropped into water. Distil off the alcohol until the percolate is reduced in weight to two hundred and fifty grammes [or 8 ounces av., 358 grains], and add the latter slowly, with constant stirring, to three thousand mils [or 101 fluidounces, 212 minims] of water. When the precipitate has subsided, decant the supernatant liquid, and wash the precipitate twice, by decantation, with fresh portions of one thousand mils [or 33 fluidounces, 6 ½ fluidrachms] each of hot water. After having drained off all of the liquid, transfer the resin to a porcelain dish and heat it to dryness on a water-bath." U. S.
"Exhaust coarsely powdered Jalap with Alcohol (90 per cent.). Recover most of the alcohol by distillation; pour the concentrated solution thus obtained into eight times its volume of Distilled Water; allow the resin that separates to subside, wash with Distilled Water, and dry at a gentle heat." Br.
Extract of Jalap was formerly official. It has been dropped from both the U. S. and British Pharmacopoeias. Resin of Jalap has taken its place in both authorities.
Properties.—Resin of jalap is officially described in the U. S. Pharmacopoeia as in "yellow to brown colored masses or fragments, breaking with a resinous, glassy fracture and translucent at the edges, or as a yellowish-gray to yellowish-brown powder, having a slight, peculiar odor, and a somewhat acrid taste. It is permanent in the air. Resin of Jalap is soluble in alcohol in all proportions; insoluble in carbon disulphide, benzene, or fixed or volatile oils. Its alcoholic solution is faintly acid to litmus. Add 1 Gm. of the powdered Resin to 10 mils of chloroform in a stoppered flask and shake the mixture occasionally during one hour. Then filter, evaporate the filtrate in a tared dish and dry the residue to constant weight at 100° C. (212° F.); it weighs not more than 0.3 Gm. Add 1 Gm. of the powdered Resin to 10 mils of ether in a stoppered flask and shake the mixture occasionally during one hour. Then filter, evaporate the filtrate in a tared dish and dry the residue to constant weight at 100° C. (212° F.); it weighs not more than 0.12 Gm. (rosin, orizaba, or other resins). It is slowly but completely soluble in 5 times its weight of ammonia water, and the solution does not become gelatinous on standing. When this solution is acidified with hydrochloric acid, only a slight turbidity appears (rosin, guaiac, or other resins). When Resin of Jalap is heated at 100° C. (212° F.), no material loss in weight is observed (water). When Resin of Jalap is triturated with distilled water, the latter does not become colored, none of the Resin dissolves (soluble impurities} , and the water does not have a bitter taste (aloin). Shake 0.02 Gm. of Resin of Jalap with 5 mils of ether, filter and evaporate the ethereal filtrate on a piece of filter paper; no greenish-blue color is produced by the application of a drop of ferric chloride T.S. to the filter paper (guaiac). One Gm. of Resin of Jalap when dissolved in 50 mils of alcohol, containing 1 mil of phenolphthalein T.S., requires not more than 0.5 mil of half-normal alcoholic potassium, hydroxide V.S. to produce a red color (acid resins} . Dissolve 0.02 Gm. of Resin of Jalap in 2 mils of glacial acetic acid and add a few drops of sulphuric acid; the mixture does not acquire a pink color (rosin)." U. S.
"In dark-brown opaque fragments, translucent at the edges; brittle, breaking with a resinous fracture; readily reduced to a pale-brown powder. Characteristic odor; taste acrid. Readily soluble in alcohol (90 per cent.). When 1 gramme of the powdered Resin is triturated with 20 millilitres of. water and filtered, the filtrate is almost colorless. ^ solution of 0.1 gramme in 10 millilitres of solution of sodium hydroxide, boiled for a few moments and cooled, when acidified with hydrochloric acid may become opalescent but not immediately turbid (absence of certain other resins). Not more than 15 per cent. of the powdered Resin is soluble in ether (absence of scammony resin)." Br.
The U. S. resin, although pure enough for practical purposes, is still colored. To obtain it colorless, the powdered jalap should be mixed, before percolation, with an equal quantity of finely powdered animal charcoal, and, previously to the introduction of this mixture into the percolator, half the quantity of animal charcoal, similarly powdered, should be packed in the bottom of the percolator. The coloring matter is thus left behind, and the resulting tincture, treated as directed in the process, yields the resin as white as starch. Resin of jalap consists of two portions, one of which is hard and insoluble in ether, the other is soft and soluble in that menstruum, the former constituting about 90 per cent. It is insoluble in oil of turpentine. (Squire.) For its chemical properties, see Jalapa. It was at one time supposed that the purgative properties resided chiefly, if not exclusively, in the hard resin, but experiments by John C. Long appear to prove that the soft resin is equally energetic.
Guaiac, rosin, and other resinous substances are said to be sometimes fraudulently added to the resin of jalap. Guaiac may be detected by the green color it produces when a few drops of solution of sodium or calcium chloride are added to an alcoholic solution of the suspected resin. (J. P. C., 3e ser., x, 357.) When pure jalap resin is dissolved in an alkaline solution, it is not precipitated by the addition of sulphuric or hydrochloric acid, having been converted, through the agency of the alkali, into an acid soluble in water. All the adulterating resins yield precipitates under the same circumstances. The resins of scammony and of fusiform jalap act in this respect like the true jalap resin, but are distinguishable by being wholly soluble in ether, while jalap resin is not. (N. R. Pharm., No. 1, 1854.)
Power and Rogerson (P. J., 1909, lxxxiii, p. 7) find that the products heretofore obtained from jalap as the active principle possesses the attributes of a homogeneous substance. They found the resin of jalap to be a body of very complex composition, but did not determine any single principle to which its purgative action might be attributed. (See Jalap for the chemistry of the resins.)
It is now generally believed that the resin of jalap is the sole purgative principle of jalap, the gummy extractive being either simply diuretic or wholly inert. To obviate the occasional harshness of the resin, it has been advised to triturate it with milk sugar, potassium sulphate, almond emulsion, or other substance calculated to separate its particles. It may be conveniently made into pills with mucilage or alcohol. (Hasselby, P. J., 2d ser., vii, 231.)
Dose, two to five grains (0.13-0.32 Gm.).
Off. Prep.—Pilulae Catharticae Compositae, U. S.; Pilulae Catharticae Vegetabiles, N. F.