Continuing Education Activity
Castor oil is a vegetable oil made from Ricinus communis, a plant common in the Eastern areas of the world. Castor oil is most well known for its laxative property; however, numerous communities report several other uses. For example, castor oil has been reported beneficial in uterine contraction, lipid metabolism, and antimicrobial activity, yet, the FDA has approved only its use as a stimulative laxative. This activity will highlight the indications, actions, and contraindications for castor oil in the use of medical procedures and constipation.
- Identify the mechanism of action of castor oil.
- Describe the potential adverse effects of castor oil.
- Review the contraindications of castor oil.
- Identify the indications for using castor oil.
The approved FDA condition for which castor oil may be useful as a stimulant laxative, which can be beneficial in constipation and medical procedures. With chronic idiopathic constipation being one of the most common GI complaints, castor oil can be of great benefit. The use, however, has declined over the years as research has produced more effective laxatives with far fewer side effects.
In diagnostic tests such as colonoscopies, it is essential to have a bowel prep before performing the procedure. Castor oil may be used in these types of procedures as it is effective in bowel evacuation. However, in these procedures, patients typically have better results and satisfaction with other laxatives such as sennosides, polyethylene glycol, and bisacodyl. In a study comparing castor oil to senna graph syrup, the senna group had fewer side effects and better bowel preparation overall. Other uses of castor oil exist; however, these indications are not FDA approved. These uses include wound healing, arthritis, headache, menstrual cramps, and labor induction. Although these uses were common in alternative medicine for hundreds of years, there is not enough scientific evidence to support these claims in modern medicine.
Although castor oil is not used often in modern medicine, its use is justified when the patient would prefer what they may feel is a more natural approach in terms of their care. With castor oil coming from the plant, Ricinus Communis, many patients may prefer its use due to its growth in nature, which inherently seems non-toxic and safer when compared to traditional medicine.  With more scientific literature on castor oil's mechanism of action, side effect profile, and toxicity, it is now completely safe and effective for a clinician to offer castor oil for its FDA-approved indications.
Mechanism of Action
The main chemical that exerts castor oil's laxative property is ricinoleic acid. In the intestine, lipase breaks down castor oil into ricinoleic acid, which activates EP3 and EP4 prostanoid receptors in smooth muscle cells. The activation of these receptors creates a transient calcium surge, which creates propulsion in the intestine. Due to this mechanism of action, castor oil falls in the stimulant laxative category, just like bisacodyl and sennosides. EP3 and EP4 prostanoid receptors are also present in the uterus, which leads to the possibility of castor oil's use for the induction of labor; however, more research is necessary on this subject.
Castor oil administration is via the oral route, as the oil needs to be broken down by intestinal lipases to have its stimulant laxative effects. An appropriate daily dose for an adult male is 15 to 60 ml per day.
The adverse effects of castor oil are a common reason why it is not used often in conventional medicine. In a study comparing castor oil to sennosides, castor oil tended to cause abdominal cramping, vomiting, bloating, and dizziness. Far fewer adverse effects were occurring with the use of other laxatives.
Few studies have also proposed that long-term use of a stimulant laxative may create a cathartic colon due to anatomic changes. Newer evidence is suggesting that a "cathartic colon" is not a real entity.
With castor oil affecting smooth muscle, recommendations include avoiding its use in pregnancy, as this can lead to premature contractions. Contraindications to stimulant laxatives also include various abdominal pathologies such as gastrointestinal obstruction, appendicitis, perforation, and inflammatory bowel disease.
As with any laxative, monitoring for electrolyte disturbances and acid-base disorders is advisable. Imbalances may occur because of the loss of bicarbonate, water, and electrolytes and worsen with diarrhea. The patient's physical exam signs may demonstrate rapid breathing, confusion, sleepiness, vomiting, and weakness, especially in the presence of electrolyte disturbances and acid-base imbalances. These issues can potentially be lethal if not addressed immediately.
The physician should also monitor patients for laxative abuse. Patients with anorexia nervosa or bulimia are especially at risk as they may try to decrease weight through laxative abuse. Laxative abuse can be detrimental due to the loss of minerals, nutrition, and electrolytes.
The castor plant, Ricinus communis, is known to have a toxic chemical called ricin. If an individual eats Ricinus seeds directly, the ricin toxin can take effect in as little as 4 to 12 hours. Signs and symptoms of ricin toxicity include gastrointestinal bleeding, shock, pulmonary edema, and inflammation. These symptoms occur due to the inactivating effect of ricin toxin on ribosomes making the body unable to create proteins. The clinician needs to provide supportive care to the patient during ricin toxicity as currently, there is no antidote. The extraction process of castor oil due to ricin's water-soluble properties negates these toxic properties. Castor oil gets purified of ricin during the extraction process. Castor oil is completely safe for human consumption with minimal toxic effects in both acute and chronic settings. Castor oil has also demonstrated no genotoxic effects. Due to its well-known safety, castor oil is also used widely for nonmedical purposes, such as lubrication, cosmetics, and coatings.
Enhancing Healthcare Team Outcomes
It is the responsibility of the health care team to be professional, ethical, and respectful of the patient's decisions in terms of their care. Due to the natural quality of castor oil, it may be the preferred treatment of choice for many patients. With increased scientific research regarding castor oil and the fact that castor oil has been in use for hundreds of years, physicians can comfortably prescribe this medication. The clinician is responsible for a thorough exam and appropriate diagnosis before determining if the use of castor oil is appropriate as various contraindications exist. After prescribing the medication, it is important to closely monitor the patient because of the different adverse effects. As the primary contact for patient care, the nurse can help the physician identify any abnormalities in patient behavior, which may be signs of electrolyte imbalances, acid-base disorders, or dehydration. Lastly, the pharmacist can help the team with appropriate dosing and drug interactions. Due to castor oil being a potent laxative, the absorption of other oral drugs may be severely affected. Overall, the interprofessional healthcare team needs to work together to ensure positive outcomes for the patient.