Efficacy of the Castor Oil-Filled Capsule Method as Preparation for Colon Capsule Endoscopy

Background: Colon capsule endoscopy (CCE) is useful as an alternative examination for patients in whom colonoscopy is difficult. The Japanese Association for Capsule Endoscopy has published a recommended regimen for CCE using castor oil, which is becoming a standard examination method for CCE in Japan. However, castor oil has an unpleasant flavor. Therefore, patient acceptance is not good. Objectives: The aims were to develop a castor oil-filled capsule and evaluate its feasibility and patient acceptance in a retrospective, comparative study. Method: A dissolution study of pig-derived gelatin capsules filled with castor oil was performed using artificial gastric juice. The CCE excretion rates within battery lifetime, CCE examination times, endoscopic colonic cleansing levels, and patient acceptability between CCE boosters with a castor oil-filled capsule and without castor oil were retrospectively compared using medical information, clinical data, and endoscopic findings at Takada Chuo Hospital from September 2016 to August 2019. Results: The castor oil-filled capsules were completely disintegrated at approximately 1–3 min in artificial gastric juice. Bowel preparation with oil-filled capsules and without castor oil was performed in 27 and 24 patients, respectively. CCE excretion rates within battery life were 100% and 91.7% (p = 0.217), small bowel transit times were 115 min and 143 min (p = 0.046), colon transit times were 168 min and 148 min (p = 0.733), and adequate colonic cleansing rates were 85.2% and 86.3% (p = 1.000) in patients using bowel preparation with and without oil-filled capsules, respectively. Regarding acceptance, the taste was not problematic in 85.2%, and tolerability for the next CCE was 96.3%. Conclusions: CCE using a castor oil-filled capsule method achieved high examination performance and sufficient patient tolerability.