The fixed oil obtained from the seeds of Ricinus communis, Linné (Nat. Ord. Euphorbiaceae). An East Indian plant; cultivated.
Description.—A pale yellow or nearly colorless viscid oil, having a faint odor, and a bland, somewhat acrid, and nauseating taste. Dose, 2 to 8 fluidrachms.
Principal Constituents.—The glyceride of ricinoleic acid (ricinolein), fixed oils, and the non-purgative ricinine.
Specific Indications.—Pain and irritation in the intestines from irritating or undigested food; intestinal, subacute inflammation, with colic, and watery or mucoid passages.
Action.—Applied externally castor oil is non-irritating, protective, and somewhat emollient. When swallowed it does not irritate the stomach, and the nausea induced is probably due to the odor and the persistence of the unpleasant clinging contact of the oil in the mouth. Upon entering the small intestines it is split by the pancreatic juice into glycerin and ricinoleic acid, and the latter induces the purgative action. Rubbed into the abdomen castor oil will also cause purgation. After the first hardened feces are removed the stools become liquid and are passed without pain or tenesmus. Castor oil seeds are poisonous, twenty having killed a child.
Therapy.—External. Castor oil is protective and slightly stimulating to denuded surfaces, and may be dropped into the eye after burns have caused an ocular ulcer. Equal parts of castor oil and balsam of Peru have been used successfully upon old, sluggish ulcers, as of the shins, and in the treatment of hypergranulation following pus infection after abdominal operations; also in healing the ulcers from burns, wounds, and abscesses.
Internal. Castor oil is one of the mildest and most satisfactory cathartics, and with the exception of sulphate of magnesium is the most commonly employed purgative. It has no irritant effect upon the stomach and operates usually in four or five hours. It is probably the best laxative for children to cleanse the intestinal tract of tainted or undigested food, poorly masticated nuts, and mucoid accumulations. It is very effective in dysentery to prepare the way for more specific medicines, especially when there is evident constipation of the upper bowel. It may prove the best agent where hardened feces are the cause of a mucoid diarrhea. The best preliminary treatment of entero-colitis in children is a purge of castor oil, after which indicated remedies have a much better opportunity to act. Owing to its thorough yet mild and unirritating character it is the most suitable laxative for constipation of children and for pregnant women before and after labor, before and after abdominal and pelvic operations, and when inflamed hemorrhoids are present. After its use in irritative diarrhoea no other agent will be needed, for the provocative cause having been removed the natural tendency of the oil is to cause constipation. Castor oil is not a good remedy for chronic constipation, for it cannot be used for prolonged periods without detriment to the patient, and probably an aggravation of the costive condition. But for an occasional purge in constipation preliminary to the use of cascara and other better laxatives for continued use nothing is better than a free dose of castor oil. In cases where there is a semipasty and tenacious light-colored stool with burning at voiding and persisting for weeks, and there is much semi-colicky uneasiness or soreness in the bowels and frequent desire to defecate, castor oil is the best purge that can be used. A single dose usually rectifies the trouble. Castor oil may be used even in inflammatory and febrile conditions.
Castor oil may be employed to assist in the expulsion of worms, giving it before and after vermifuges and taeniacides. It should not, however, be given if aspidium (male fern) has been used, for it increases the poisonous absorption of the latter.
The great drawback to castor oil is its nauseous taste, which may be more or less disguised by peppermint and other aromatics. Peppermint lozenges may be eaten immediately before and after swallowing it; it has been advised in coffee, sweet cider, ale, milk, and broth, but we do not favor the giving of nauseous medicines in common beverages and foods, lest a disgust for the latter be engendered. The following is the best method we know of for administering castor oil: Squeeze into a suitable warmed glass a small quantity of orange juice, and thoroughly rinse the inner surface of the glass with it. Place the dose of oil upon the juice and cover with more juice. Then having moistened the mouth completely with a portion of the orange juice quickly swallow the mixture within the glass. If this is well carried out the oil will not adhere to the mucosa nor will it be tasted. When a strong purgative is needed, equal parts of aromatic syrup of rhubarb (or neutralizing cordial or glyconda) and castor oil may be given in doses of one to two fluidounces.