CASTER OIL

Caster oil is a fixed oil obtained from the seeds of Ricinus copmmunis LINN. (Euphorbiaceae). The plant is an annual in temperate climate, or a tree, attaining the height of 15 meters in the tropics. The fruit is 3-celled spiny capsule each cells containing an ovoid albuminous seed. The plant is indigenous to India, Brazil, Russia, Europe, U.S.A., and various parts of Africa.
Preparation:
Castor oil is prepared by passing the seeds through a decorticator having rollers with sharp cutting edges which beak the testa but do not injure the kernel, then testas are separated by means of sieve and compressed air, and kernels are subjected to pressure. The yield of “cold pressed” oil obtained by hydraulic pressure represents light coloured, good grade where as the remainder solvent extract yield a darker lower grade.
Description:
Castor oil is a pale yellowish or almost colourless transparent, viscid liquid. It has a faint mild odour and a bland, followed buy a slightly acrid and usually nauseating taste.
Constituents:
It consists chiefly of triglycerides of ricinoleic acid (80%). It also contains small amount of other glycerides, the fatty acids of which include oleic (70%), linoleic (4%) stearic (2%), hydroxystearic acid.
Physical and chemical characteristics:
Specific gravity at 20, 0.963-0.964; optical Rotations Index: at 40, 1.4965-1.4730; saponification value: 177-178; Iodine Value: 82-90; Acid Value: not more than 4. Reichert Meissl No. 144-150; Solubility: Soluble in 2-5 parts of 90% alcohol, miscible with dehydrated alcohol, ether, and glacial acetic acid. identification tests: Mix sample of castor oil with half and twice the volume of petroleum ether. Note that while this is miscible with the former it is insoluble in the latter.
Action and uses:
It is a purgative and its action being exerted in 4-8 hours. It is given in acute diarrhea particularly due to food poisoning. Castor oil is emollient and is used in preparations such as zinc and castor oil ointment, sterilized castor oil (sterilized by dry heat) is soothing application when dropped into the eye after removal of foreign bodies, is used as an oily vehicle for eye drops.
Toxic Effects:
The administration of castor oil by mouth, particularly in larger doses, may produce nausea, vomiting, colic and severe purgation.