If poor bowel prep before capsule endoscopy is the problem, could castor oil be the solution? 

A group of Japanese researchers believe that a couple of generous shots of castor oil before capsule endoscopy can achieve good bowel cleansing with less fluids than large-volume solutions, thus improving adherence to prep protocols before the procedure (World J Gastrointest Pharmacol Ther 2021;12[4]:79-89).

“Current capsule preps can lead to poor cleansing, and capsule batteries can expire before exiting the colon, so the patient is given extra boosters that stimulate more bowel movements after swallowing the capsule,” said Shai Friedland, MD, a professor of medicine in the Department of Gastroenterology and Hepatology at Stanford Medicine, in California, who was not involved in the research. “While there have been numerous studies of a variety of regimens, unfortunately, the preparation is still challenging for patients and the results are not always adequate.”

In an attempt to overcome the limitations of current prep regimens—including the challenge of consuming over 4.5 L of polyethylene glycol (PEG) typically required for capsule prep—Kota Takashima, MD, of Kindai University Faculty of Medicine, in Osaka, and his colleagues enrolled 20 patients set to undergo capsule endoscopy (PillCam, Medtronic) for suspected colorectal disease to follow a pared-down prep regimen of 3.5 L of fluid, including castor oil boosters.

The regimen included consuming 230 mL of magnesium citrate and water the day before endoscopy, 1.5 L of PEG with water on the morning of the procedure, 20 mL of castor oil and 750 mL of PEG mixed with water one hour later, another 500 mL of PEG with water one hour subsequently, and then 230 mL of magnesium citrate with water and another 20 mL of castor oil after waiting another hour.

According to Dr. Takashima’s team, 17 patients tolerated the regimen. Three others had an aversion to the other liquid laxatives in the regimen except the castor oil.

Approximately 70% of patients achieved good or excellent colon cleansing, while the rest achieved good or fair cleansing, the researchers reported. Capsules were excreted after a mean 236 minutes, and 88% had battery life remaining at the time of excretion.

Clinicians identified colon polyps in 82% of patients and colonic diverticulum in 33% of the patients. The researchers reported that over 70% of participants said the overall capsule procedure was “good” or “very good.”

However, Dr. Friedland expressed skepticism that castor oil meets the challenge of finding a tolerable capsule prep.

“Not only does castor oil smell and taste terrible, it has a long history of being used as a punishment for misbehaving children and as a device for torture and humiliation of political opponents by the Fascists under Mussolini,” he said. “If we want to encourage our patients to comply with colon cancer screening, we may want to consider something other than a castor oil bowel prep.”

Dr. Friedland said the current study is limited by a small sample size with no control group, and the regimen needs to be tested in a randomized controlled study with more patients.

—David Wild

Dr. Friedland reported serving as a consultant to Capsovision.