Before the widespread use of PEG, the enema was an important component of bowel preparation. The increased discomfort and lack of improvement in the quality of bowel cleansing have minimized the popularity of this agent. The enema appears to maintain its role as an adjunct in patients who present for colonoscopy with inadequate bowel preparation.
The need to ingest a large volume of fluid has been one of the greatest challenges in successful administration of bowel preparations. Laxatives such as senna, bisacodyl, and magnesium citrate have been used for their additive cathartic effects, reducing the volume of PEG required for cleansing.
GI symptoms such as nausea, bloating, and gas also limit the tolerability of bowel preparations. These symptoms can be alleviated with use of adjunct agents. Metoclopramide has been shown to reduce the occurrence of nausea and bloating. Simethicone can reduce bloating and gas, and it also may be used to eliminate foam formation and improve visualization for colonoscopy screenings.[14,24,26]
US Pharmacist. 2013;38(12):30-34. © 2013 Jobson Publishing