Clinical trial: an efficacy evaluation of reduced bisacodyl given as part of a polyethylene glycol electrolyte solution preparation prior to colonoscopy

Background In an attempt to further improve patient preparation experience with reduced volume gut lavage solutions using 2-L sulphate-free electrolyte lavage solution plus 20-mg bisacodyl (HalfLytely with Bisacodyl Tablets Bowel Prep Kit, Braintree Laboratories, Inc., Braintree, MA, USA), a low bisacodyl dose preparation was developed using 10 mg bisacodyl. Aim To compare preparation methods using the 10- or 20-mg bisacodyl with 2-L sulphate-free electrolyte lavage method. Methods At 10 US centres, 455 patients undergoing colonoscopy for routine clinical indications were equally randomized to receive 10- or 20-mg bisacodyl with 2-L sulphate-free electrolyte lavage method. Colonoscopists rated the efficacy of colon cleansing, blinded to the preparation assignment. Results Physician assessment of colon cleansing showed no difference between those randomized to receive the 10- or 20-mg bisacodyl preparations (P = 0.52). The 10-mg preparation had lower symptom scores for cramping (P < 0.001) and overall discomfort (P = 0.001). Other reported adverse experiences were few, mild and not different between groups. Conclusion Two-litre sulphate-free electrolyte lavage method solution with 10-mg bisacodyl is as effective as the 20-mg bisacodyl preparation for cleansing the colon prior to colonoscopy. The 10-mg bisacodyl regimen has an improved safety profile, with significantly reduced cramping, nausea and overall discomfort.