A randomized controlled trial of high volume simethicone to improve visualization during capsule endoscopy

Background: The optimal dose of simethicone before capsule endoscopy is unknown. Prior studies have reported inconsistent cleansing, with some showing improved visualization only in the proximal small intestine. We hypothesized a higher volume of simethicone may improve cleansing and diagnostic yield, especially in the distal small bowel. Methods: A phase III randomized controlled trial was conducted comparing high volume (1125 mg simethicone in 750 ml water) versus standard volume (300 mg simethicone in 200 ml water) solutions, both at 1.5 mg/ml. The primary outcome was adequate bowel preparation, defined as a KOrea-CanaDA (KODA) score >2.25, overall and stratified by the proximal and distal half of the small bowel. Secondary outcomes included mean KODA score, diagnostic yield, completion rate, and adverse events. All analyses were intention-to-treat. Results: A total of 167 patients were randomized (mean (SD) age 58.7 (15.7), 54% female) and the most common indication was obscure gastrointestinal bleeding (71.7%). Adequate cleansing was achieved in 39 (50%) patients in the high volume group and in 39 (48%) patients in the standard volume group (RR 1.04, 95% CI 0.76–1.43, p = 0.82), with no differences observed in the proximal half (71% vs 64%, p = 0.40) or the distal half -of the small bowel (36% vs. 37%, p = 0.88). There was no differences in the mean (SD) KODA score (2.20 (0.41) vs. 2.18 (0.44), p = 0.73), diagnostic yields (53% vs. 56%, p = 0.71), or completion rates (both 95%). One adverse event, nausea, occurred in the control group. Conclusion: High volume simethicone does not improve visualization during capsule endoscopy. Clinical trial registration: Clinical trial: NCT02334631.