Efficacy of low-dose versus high-dose simethicone with polyethylene glycol for bowel preparation: A prospective randomized controlled trial

Background and Aim Additional simethicone (SIM) can improve adequate bowel preparation and adenoma detection rate (ADR). However, there is no consensus on the optimal dose of SIM. In this study, we compared the adequate bowel preparation rate with supplementation of split-dose 2 L polyethylene glycol (PEG) with low-dose SIM (200 mg) versus high-dose SIM (1200 mg). Methods This was a prospective, randomized, observer-blinded trial involving consecutive subjects undergoing colonoscopy. The primary outcome was adequate bowel preparation as assessed by Boston Bowel Preparation Scale (BBPS) score. Results Four hundred subjects were randomly allocated to low-dose SIM or high-dose SIM group. Baseline characteristics were comparable in the two groups (P > 0.05). No significant between-group differences were observed with respect to total bubble scale (BS) (8.49 +/- 1.00vs8.39 +/- 1.10,P = 0.07), total BBPS score (8.70 +/- 0.81vs8.29 +/- 1.18,P = 0.98), ADR (33.68%vs31.79%,P = 0.69) or withdrawal time (13 [range, 10-16] minvs13 [10-15] min,P = 0.96). The intubation time in low-dose SIM group was significantly shorter than that in high-dose SIM group (8 (4-16) minvs10 [6-17] min,P = 0.04). In addition, BS scores as well as diminutive ADR in right colon were superior in the low-dose SIM group (2.68 +/- 0.59vs2.52 +/- 0.73,P = 0.03 and 54.29%vs30.30%,P = 0.046, respectively). Conclusion Addition of low-dose SIM to split-dose 2 L PEG was as effective as addition of high-dose SIM with respect to adequate bowel preparation, ADR and patient tolerance. However, low-dose SIM was superior with respect to intubation time, right colon BS scores, right colon diminutive ADR and cost savings.