Oleum Ricini (U. S. P.)—Castor Oil.

Fig. 184. Ricinus communis. Photo: Ricinus communis 11. Preparations: Emulsion of Castor Oil - Compound Mixture of Oils

"A fixed oil expressed from the seed of Ricinus communis, Linné (Nat. Ord.—Euphorbiaceae). It should be kept in well-stoppered bottles"—(U. S. P.).

Botanical Source.Ricinus communis, the Castor-oil bush, in the United States, is a herbaceous annual, with a white, frosted, or glaucous, hollow, smooth stem, of a purplish-red color upward. The root is long, thick, and fibrous. The leaves are large, alternate, deeply divided into 7 or 9 lanceolate segments, peltate, palmate, serrate, 4 to 12 lines in diameter, and on long, tapering, purplish petioles. The flowers are borne in long, green, and glaucous spikes, springing from the divisions of the branches; males from the lower part of the spike, females from the upper. The capsule is prickly, 3-celled, and 3-seeded; the seeds ovate, shining, and black dotted with gray (L.—W.)

History.—Ricinus communis, or Palma Christi, is an East Indian plant, in which country it attains the size of a tree. In the United States, where it has become naturalized, it seldom grows higher than 8 or 10 feet, flowers in July and August, and matures its seeds in August and September. The plant is much grown in California for its oil, also in Italy. The fixed oil of the seeds is the castor oil of commerce, and was known to the ancient Egyptians. The seeds are poisonous, about 4 lines in length, 3 lines in width, and about 1 ½ lines in thickness, and consist of a smooth external coat, covering a thick, hard, and dark-brown shell, composed of two layers which inclose the white nucleus or oleaginous kernel, which has within it a large, dicotyledonous, leafy embryo. A nongriping cathartic oil, Tambor oil, is obtained from a Central American euphorbiacea, Omphalea oleifera, Hemsley. (For a detailed historical account of the castor-oil plant, see H. Stillmark's dissertation on Ricin, 1889.)

Preparation.—Castor oil may be obtained by several methods, mostly by warm or cold pressure after the seeds are deprived of their husks. The cold-drawn oil is the most esteemed, although the U. S. P. does not expressly demand it. In order to remove the acridity of the fresh oil, and to coagulate albuminous matter, the oil is purified by repeatedly boiling it with water. By cold expression the seeds yield 40 to 45 per cent of oil, and a smaller quantity upon subsequent warm expression. The latter oil, however, is not used medicinally. The poisonous principle contained in the seed remains in the press-cake, and is destroyed by boiling with water.

Description and Tests.—Castor oil, as demanded by the U. S. P., is "a pale-yellowish or almost colorless, transparent, viscid liquid, having a faint, mild odor, and a bland, afterward slightly acrid, and generally offensive taste. Specific gravity, 0.956 to 0.970 at 15° C. (59° F.). Soluble in an equal volume of alcohol, and in all proportions in absolute alcohol, or in glacial acetic acid; also soluble at 15° C. (59° F.), in three times its volume of a mixture of 19 volumes of alcohol and 1 volume of water (absence of more than about 5 per cent of most other fixed oils). With an equal volume of benzin, it forms, at 15° C. (59° F.), a turbid mixture, but at 17° C. (62.6° F.), it yields a clear solution. When exposed to the air in a thin layer, it slowly dries to a varnish-like film. When cooled to 0° C. (32° F.), it becomes turbid, with the separation of crystalline flakes, and at about -18° C. (-0.4° F.) it congeals to a yellowish mass. If 3 Cc. of the oil be shaken for a few minutes with 3 Cc. of carbon disulphide and 1 Cc. of sulphuric acid, the mixture should not acquire a blackish-brown color (absence of many foreign oils)"—(U. S. P.).

This oil is one of the heaviest and most viscid of the fixed oils, and is distinguished from all other oils except croton oil, by its ready solubility in alcohol and acetic acid in the cold. Its remarkable insolubility in an excess of benzin (see above) may be overcome by the admixture of a third fatty oil, e. g., lard oil. When exposed to the air in bulk, its viscidity increases, and the oil becomes rancid; in thin layers it slowly dries, it also yields with nitrous acid (according to Pharmacographia, 6 parts of castor oil warmed with 1 part of starch and 5 parts of nitric acid of specific gravity 1.25) solid ricin-elaïdin. Thus castor oil shares the conspicuous properties of both drying and non-drying oils. Unlike most other fixed oils, some specimens of castor oil, e. g., East Indian oils, show a right-handed optical rotation. When heated to temperatures above 100° C. (212° F.), castor oil becomes altered, the characteristic oenanthol being among the products of decomposition (see below).

It is stated that rancid, acrid castor oil may be deprived of its disagreeable odor and taste, as well as of acrimony, by boiling it for 15 minutes with water and a little calcined magnesia. Castor oil, in addition to its medicinal uses, is much employed in the preparation of lubricants and cheap soaps, and in the making of turkey-red oil, which is used as a mordant in dyeing cotton with alizarin dyes.

Chemical Composition.—I. SEEDS. According to Geiger, the seeds consist to about one-fourth of the husks, and three-fourths of nucleus. The seed-coats contain tasteless resin and extractive, 1.91; brown gum, 1.91; ligneous fiber, 20.00, The nucleus of the seeds contain fatty oil, 46.19; gum, 2.40; casein (albumen), 0.50; ligneous fiber, with starch, 20.00; loss or moisture, 7.09 (P.). They also contain a peculiar and acrid principle which does not enter the oil, for the seeds are powerfully active after the oil has been expressed. The active poisonous principle, according to Stillmark (loc. cit., 1889), is an unorganized albuminous ferment, called ricin. In air-dry seeds it is present in the quantity of about 3 per cent. It is obtained in largest amount by extracting the press-cake cold, with a 10 per cent solution of sodium chloride, and precipitating the filtrate with magnesium sulphate. The poison is destroyed by boiling with water, although not by dry heat. It is not a glucosid.

II. OIL.—According to Alfred H. Allen (Com. Org. Anal., Vol. II, Part I, 3d ed., 1889, p. 156), castor oil is free from palmitin or olein, but contains small amounts of stearin. Its chief constituents are ricinolein (C3H5[C18H33O3]3), isoricinolein, and dihydroxystearin. RICINOLEIC ACID (C18H34O3) is the principal acid of the oil; it forms a thick oily liquid, solidifying below 0° C. (32° F.), soluble in alcohol and ether. It does not absorb oxygen from the air, although as an unsaturated acid it absorbs 2 atoms of bromine. By the action of nitrous acid it is slowly converted into its stereo-isomer, ricinelaïdic acid, which crystallizes in needles melting at 50° C. (122° F.). By distillation under diminished pressure, ricinoleic acid yields among other products oenanthol (oenanthic or heptoic aldehyde C7H14O or C6H13.CHO), a highly refractive liquid of a characteristic odor, boiling at 154° C. (309.2° F.). Castor oil also yields oenanthol when rapidly distilled. In addition, oenanthic acid (C6H13.COOH), acrolein, and other substances are formed. In this connection we may refer to oenanthic ether (C6H13.COOC2H5), a constituent of the bouquet of wines, which is prepared by conducting dry hydrochloric acid gas into a solution of oenanthic acid in absolute alcohol. It boils at 188° C. (370.4° F.).

Action, Medical Uses, and Dosage.—The castor-oil seed or bean is a powerful cathartic and gastric irritant, and has proved fatal to man when taken to the extent of 20 seeds at once. Yet the oil expressed from it is only a mild cathartic, operating promptly, producing thin, feculent, but not watery stools, and causing but little griping or nausea. From its mildness of action, it is especially adapted to young children, pregnant or puerperal females, likewise in hemorrhoidal affections, colic, diarrhoea, dysentery, enteritis, after the reduction of hernia, obstinate constipation, collections of indurated feces, accumulation of acrid secretions, and in worms. It is frequently used to remove constipation, and also in diarrhoea when due to undigested material. When throat and skin disorders depend upon intestinal accumulations, castor oil is an efficient purgative. One part of oil of turpentine mixed with 3 or 4 parts of castor oil increases its purgative and anthelmintic effect. The greatest objections to this cathartic are its nauseous taste and its tendency to cause sickness or unconquerable disgust. This may be overcome by adding to 1 pint of the oil ½ fluid ounce each of oils of origanum and wintergreen, or 1 ounce of sassafras oil; the dose of this may be given in sweetened water. Any other aromatic oils will answer equally as well. When not contraindicated it may be taken in wine, spirituous liquors, or the froth of beer, likewise in cinnamon or peppermint water. I find it a very pleasant mode of administration to boil the dose of oil with about a gill of good sweet milk for a few minutes, sweeten with loaf-sugar, and flavor with essence of cinnamon or other favorite aromatic; it somewhat resembles custard in its taste and appearance, and is readily taken by even the most delicate stomach (J. King).

Stuncke states that castor oil saponifies readily with alkalies, and gives with soda a white solid soap, which, in the form of pills, is a certain and agreeable purgative. M. Parola proposes an ethero-alcoholic extract and the ethereal and alcoholic tinctures of the seeds as a substitute for the oil; he states that the above tinctures have a purgative action four times as strong as the oil, are less irritating, and remain unalterable in all climates. As an enema, castor oil may be used in the quantity of 2 or 3 fluid ounces mixed with some mucilaginous liquid. Externally, it has been recommended in itch, ringworm, and other cutaneous diseases. Daily applications of castor oil to warts is said to remove them in a few weeks. Dose for an adult, 1 or 1 ½ fluid ounces; for an infant, 1, 2, or 3 fluid drachms, according to its age. Equal parts of castor oil and copal varnish form an excellent local application for hemorrhoidal affections. A hairwash for keeping the hair from falling, and cleansing it of dandruff, is sold by the perfumers, and is made as follows: Take castor oil, ½ pound; strongest alcohol, ½ pint; powdered cantharides, 48 grains; oil of bergamot, ½ ounce; otto of roses, 4 drops. Mix, let them stand for 7 days, frequently shaking, and then filter, and keep in well-closed bottles.

CASTOR-OIL LEAVES.—According to Dr. J. O. McWilliam, the natives of the Cape Verde Islands use the leaves of the castor-oil plant, which they term "Bofareira," for accelerating and increasing the flow of milk, in cases where it is tardy in appearing or deficient in quantity, and also in cases of emergency, where the females are not child-bearing, or have not suckled a child for many years. The white plant, known by the light-green color of the leaf-stem, is used instead of the red, having a purplish-red leaf-stem. The breasts are frequently fomented, and the boiled leaves placed upon the breasts in the form of a poultice. This operation is frequently repeated, and in obstinate cases the thighs and generative organs are exposed to the vapor from the decoction. One, two, or three days are required before the child can procure a supply of milk from the breasts of persons thus treated—according to circumstances.

Women with well-developed breasts are most easily affected by it, while those with small and shriveled breasts have the uterine system acted upon, bringing on the menses, if their period be distant, or causing their immoderate flow if their advent be near. Exposure to cold is carefully avoided by women brought under its influence; they scrupulously abstain from wetting the hands or feet with cold water. It is said to affect virgins of adult age, similar to child-bearing women. It sometimes produces swelling and pain in the breasts and axillary glands, pain in the back, and an increase of a leucorrhoeal discharge.

This remedy, and the Red bofareira, both of which are common to this country, have been tried by physicians, as an emmenagogue, and the results have been sufficiently favorable to render further investigation very desirable.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.