Adjuncts to colonic cleansing before colonoscopy

Abstract

Pre-procedural cleansing of the bowel can maximize the effectiveness and efficiency of colonoscopy. Yet, efficacy of the current gold standard colonic preparation method - high-volume oral administration of purgative agents 12-24 h prior to the procedure - is limited by several factors, such as patient compliance (due to poor palatability and inconvenience of the dosing regimen) and risks of complications (due to drug interactions or intolerance). Attempts to resolve these limitations have included providing adjunctive agents and methods to promote the colonic cleansing ability of the principal purgative agent, with the aim of lessening unpleasant side effects (such as bloating) and reducing the large ingested volume requirement. Several promising adjunctive agents are bisacodyl, magnesium citrate, senna, simethicone, metoclopramide, and prokinetics, and each are being investigated for their potential. This review provides an up to date summary of the reported investigations into the potencies and weaknesses of the key adjuncts currently being applied in clinic as supplements to the traditional bowel preparation agents. While the comparative analysis of these adjuncts showed that no single agent or method has yet achieved the goal of completely overcoming the limitations of the current gold standard preparation method, they at least provide endoscopists with an array of alternatives to help improve the suboptimal efficacy of the main cleansing solutions when used alone. To aid in this clinical endeavor, a subjective grade was assigned to each adjunct to indicate its practical value. In addition, the systematic review of the currently available agents and methods provides insight into the features of each that may be overcome or exploited to create novel drugs and strategies that may become adopted as effective bowel cleansing adjuncts or alternatives.

Keywords: Colonoscopy, Cathartics, Adjuncts, Purgative agents, Bowel preparation

Core tip: Fair bowel cleansing is a prerequisite for unobstructed visualization in colonoscopy. Since the gold standard self-managed preparation procedure and purgative agent-related complications can limit thorough cleansing, several adjunctive agents and methods have been developed. Clinical experience with these adjuncts have led to some being advocated by endoscopists as useful accessory drugs and to others being criticized for causing further adverse effects or providing insufficient additional benefit. In this article, we reviewed several of the agents that are currently used as colonic cleansing adjuncts and provide a subjective evaluation of their practical value based on their evidentiary strengths and drawbacks.