VA Class:GA204

ATC Class:A06AB05

AHFS Class:

• Cathartics and Laxatives 56:12

Generic Name(s):

• Castor Oil

Castor oil, a stimulant laxative, is a fixed oil obtained from the seeds of Ricinus communis .

Administration

Castor oil is administered orally. Emulsions or aromatic preparations somewhat mask the disagreeable taste of castor oil. Containers of castor oil emulsion should be shaken before using, and the emulsion may be mixed with 120-240 mL of water, milk, fruit juice, or soft drink before administration.

Dosage

The usual adult dose of castor oil for constipation is 15 mL; however, castor oil usually should be reserved for total colonic evacuation, such as prior to surgery or radiologic, sigmoidoscopic, or proctoscopic procedures. For these purposes, the usual dose of castor oil is 15-60 mL for adults and children 12 years of age and older, 5-15 mL for children 2-11 years of age, or 1-5 mL for children younger than 2 years of age, administered as a single dose about 16 hours before the surgery or procedure. To prepare for colonic surgery or radiologic, sigmoidoscopic, or proctoscopic procedures, the patient should receive a residue-free diet one day before the surgery or procedure and a cleansing rectal enema (e.g., tap water, soap suds, saline laxative, bisacodyl) on the day of the examination. Additionally, standardized senna fruit extract may be administered 4 hours after castor oil.

Pharmacokinetics

The extent of GI absorption of castor oil is unknown. In the small intestine, castor oil is hydrolyzed by pancreatic lipase to its active principle, ricinoleic acid. Ricinoleic acid is absorbed to a small extent and subsequently metabolized like other fatty acids. Loose bowel movements usually occur within 2-3 hours following oral castor oil administration.

Chemistry and Stability

Chemistry

Castor oil, a stimulant laxative, is a fixed oil obtained from the seeds of Ricinus communis. The drug, which is an ester of ricinoleic acid, occurs as a pale yellowish or almost colorless, transparent, viscid liquid having a faint, mild odor and a bland, characteristic taste. The oil has a specific gravity of 0.957-0.961. Castor oil is soluble in alcohol. Aromatic castor oil is a solution of castor oil in alcohol containing suitable flavoring agents. Aromatic castor oil contains not less than 95% castor oil and not more than 4% alcohol.

Stability

To avoid rancidity, castor oil should not be exposed to temperatures above 40°C. Castor oil emulsions should be protected from freezing.

Additional Information

For further information on pharmacology, uses, cautions, drug interactions, and dosage and administration of castor oil, see the Cathartics and Laxatives General Statement 56:12.