Castor Oil

CASTOR OIL, castor oil, Oleum Ricini, s. Oleum Castoris, s. 01. Palmae Christi, is obtained from the seeds of the castor oil tree (castor bean, Ricinus communis L.), a member of the Euphorbiaceae family, cultivated in Africa, India, America, northern Italy, and various regions of the USSR (Transcaucasia, Turkestan, Terek district, Kuban district, Odessa region, etc.). The native home of castor is tropical Africa and India, where it is a tree; in southern Europe it is a shrub, and in central Europe an annual herbaceous plant. European and American varieties of castor are distinguished. The first gives smaller seeds but with a higher oil yield. The seed of castor (Semen Ricini, s. Cataputiae majoris) is 8–18 mm long, up to 12 mm wide, and 7.5 mm thick, oval in shape, with a dense coat covered with red-brown and black stripes. The seeds contain 45–65% fats, up to 20–25% protein substances, and among them up to 3% of the strongly toxic ricin, which is destroyed by boiling; in the pharmaceutical preparation, castor oil contains no ricin. Castor oil is obtained after cleaning the seeds of their coat by pressing them 1–2 times at low temperature; in this way up to 40–45% oil is obtained. By heating with water and using solvents (carbon disulfide, etc.), an additional 7% of oil can be obtained, but of a poorer quality and therefore used not for pharmaceutical purposes but exclusively for technical purposes. The pharmaceutical preparation is obtained from the first portion pressed at low temperature. Repeated boiling of the oil with water destroys any ricin that may be present in it. Further heating frees the oil from water and filters it. Castor oil is a thick, pale yellow liquid (castor oil obtained not at low temperature but by heating has a more saturated yellow color or even yellow-red); when stored with access to air it easily becomes rancid, acquiring an unpleasant smell and taste. Specific gravity 0.950–0.970, rotation in a 200 mm tube at 20° = 23.4–26.1°. It dissolves in all proportions in anhydrous alcohol, ether, and acetic acid, and only partially in petroleum ether (in contrast to most other oils). On air it slowly thickens, forming a viscous mass. A mixture of 3 cm³ castor oil, 3 cm³ chloroform, and 1 cm³ concentrated sulfuric acid, when shaken for several minutes, should not show a brown or dark brown coloration (the latter occurs with the admixture of foreign oils, as well as with castor oil pressed by heating). Castor oil contains about 80% glycerides of ricinoleic (oxyoleic) acid [CH₃(CH₂)₅CH₂CH:CH(CH₂)₇.C_OOH] along with glycerides of isoricinoleic, tristearin, diostearin, and oxi-stearic acids. Free ricinoleic acid is present in good oil only up to 0.4–0.6%. In extracted oil or oil pressed by heating it is up to 15%. Castor oil became known in Europe in the second half of the 18th century and is one of the most popular laxatives in medicine. Taking 15–30 g of castor oil orally causes 1–2 liquid or mushy stools after 5–6 hours (on average), usually not accompanied by any pronounced pain. After the laxative action caused by castor oil, bowel movements are usually absent for 1–2 days. The active principle of castor oil is ricinoleic acid, which is released from its esters under the influence of pancreatic juice, bile, and intestinal juice. Salts of ricinoleic acid, which do not change in the intestine, such as magnesium ricinoleate, do not possess laxative action (the same fate befalls the amide of ricinoleic acid). A more detailed study of the action of castor oil (Magnus and his school) showed the following: castor oil, like other fats, delays gastric movements and prolongs the gastric phase of digestion; however, the presence of free ricinoleic acid in the oil can, on the contrary, accelerate the passage of the oil into the intestine, and a high content of it can lead to nausea and vomiting, occurring some time after taking castor oil (the reflux of duodenal contents, already containing split ricinoleic acid, may also play a role in these phenomena). Saponification and absorption of castor oil occur in the upper part of the small intestines and it usually does not reach the large intestines. The freed ricinoleic acid causes excitation of pendular and peristaltic movements of the intestine, as a result of which finely divided intestinal contents quickly pass into the large intestines, where defecatory movements begin immediately. Due to the rapid passage of intestinal contents through the colon and the suppression of antiperistaltic movements that prolong the residence of this content in the intestine, water does not have time to be absorbed, and the stools are usually mushy or even liquid. A peculiarity of the action of castor oil is that the presence of unsplit oil moderates the irritating action of ricinoleic acid and facilitates the sliding of the denser parts of the intestinal contents. It was held that in addition to the direct irritating action of ricinoleic acid on the intestine, by causing the precipitation of calcium salts it thereby removes the inhibitory influence on peristalsis of the splanchnic nerves, but experiments on isolated intestine show that this is unlikely to be of great importance (works of Magnus's school). The advantages of castor oil over other laxatives consist in the "gentleness" of its action, not accompanied by painful peristalsis, colics, tenesmus, or any inflammatory phenomena in the intestine, but limited to 1–2 stools and at the same time leading to complete cleansing of the intestine. Thus, it is a laxative that spares the patient's strength. Special indications for preferring castor oil over other laxatives are, on the one hand, the patient's weakness (various febrile diseases, convalescence, etc.), and on the other, the presence of various inflammatory phenomena in the abdominal organs (such as where the appointment of a laxative is not itself contraindicated). Castor oil is specially prescribed in the treatment of dysentery, for expelling worms after taking an anthelmintic (one should, however, beware of prescribing castor oil after taking fern extract, as cases of fatal poisoning caused by the apparently better absorption of the toxic principles of the fern dissolved in castor oil have been described), at the beginning of febrile diseases, as a laxative in pregnancy, etc. It should be borne in mind that frequent intake of castor oil disturbs appetite, digestion, and causes constipation. In addition to administration per os, a laxative effect also occurs upon administration of castor oil per rectum (adding castor oil to a usual enema). Due to the unpleasant taste and smell when taking castor oil, a number of measures are recommended, such as taking it in black coffee or beer, in the form of an emulsion, adding a few drops of chloroform, Tincturae Menthae, lemon juice, etc. Slight warming of castor oil makes it more liquid and more convenient for rapid swallowing. For the same purpose of facilitating intake, castor oil is prescribed in gelatin capsules; the taste of castor oil is also corrected and intake is facilitated by prescribing castor oil in the form of a ready-made emulsion: Rp. 01. Ricini 40,0, Gummi arabic. 15,0, Aq. dest. q. s. M. f. 1. art. emulsio 150,0, Sir. Amygdalar. 50,0. When prescribing this emulsion for dysentery, 1.5–2.0 T-rae Opii is added, which reduces pain and lowers the intensity of peristaltic contractions (as Magnus showed, morphine does not eliminate the laxative action of castor oil). Emulsion of castor oil is prescribed especially often in pediatric practice. Doses of castor oil for adults: 1–2 tablespoons (15.0–30.0), for children from a teaspoon to a tablespoon (3.0–15.0) per dose. Castor oil is also used in dermatological practice to soften the skin in seborrhea sicca, to remove crusts, as a vehicle, and finally as a weakly irritating agent in various prescriptions intended to stimulate hair growth. Poisoning by castor seeds. Ricin, contained in castor seeds in an amount up to 3%, is a strongly toxic substance, which in a sufficiently purified form kills a rabbit already in a dose of 0.001 mg per 1 kg of weight. Absent in the pharmaceutical preparation of castor oil, it may be contained in hot oil extracts as well as in seed pressings. Ricin poisoning can occur in humans by eating the seeds; such cases of poisoning are known in children who had contact with castor as a decorative plant; even 1–2 seeds can cause severe poisoning. Cases of poisoning have also been observed in domestic animals that received castor cake as feed. Due to its strong toxicity and a number of other properties mentioned below, ricin is similar to bacterial toxins and is often called a "plant toxin," "phytotoxin," and sometimes "toxalbumin," although its protein nature is doubtful. It causes strong irritation, inflammation, and necrosis of the mucous membrane of the digestive tract, with which is associated the appearance of vomiting, bloody diarrhea, colics, etc. Upon absorption, it causes agglutination of erythrocytes and hemolysis. Death occurs with convulsions and collapse.

Like bacterial toxins, it possesses antigenic properties, causing the formation of antitoxins in the body (Ehrlich; 1891).-Treatment of poisoning is symptomatic: gastric lavage via a tube, administration of emetics in case vomiting has not yet occurred, then demulcents (milk, egg white), opiates, and with signs of collapse—stimulants and various procedures leading to warming of the body, etc. In addition to ricin, the seeds of the castor plant contain the toxic alkaloid ricinin, which is 1-methyl-3-cyano-4-methoxy-2-pyridone. OCH₃ \/ CH₃ T./K. Since it has not been pharmacologically studied, it is unclear what role it plays in the picture of castor seed poisoning. In the pharmaceutical preparation of castor oil, it, as well as ricin, is absent.