Colonoscopy preparations. The Medical Letter 2005;47(1212):53-4.
Several methods are available to cleanse the bowel before colonoscopy. Polyethylene glycol (PEG) electrolyte solutions, which pass through the bowel without absorption, are the safest choice for patients who cannot tolerate a fluid load. About 10% of patients are unable to drink the required 4 liters due to salty taste, large volume, and the resultant nausea and abdominal fullness. One approach uses 2 liters of PEG solution together with four delayed-release tablets of bisacodyl a few hours before the procedure. In another approach to improve taste, the laxative powder PEG 3350 (Miralax) has been mixed with Gatorade, but the sugars in Gatorade may be converted to flammable gases, which theoretically could ignite when electrocautery is used to remove a polyp. Sodium phosphate (Fleet Phospho-Soda) costs less than $3 compared to $18 to $49 for PEG solutions, but it can result in bowel lesions that mimic inflammatory bowel disease and a decrease in intravascular volume that leads to dizziness, fainting, falls, or seizures. Sodium phosphate is contraindicated in patients with congestive heart failure, gastric obstruction, renal failure, or ascites; it should be used with caution in the elderly. According to Medical Letter consultants, the best mix of efficacy, tolerability, and safety in cleansing the bowel for colonoscopy is the combination of 2 liters of a PEG solution plus 4 delayed-release bisacodyl tablets.