MoviPrep (Salix) is a new polyethylene glycol (PEG)-based bowel cleansing preparation approved for use in adults prior to colonoscopy. It contains ascorbic acid, which acts as an additional cathartic and flavoring agent, and requires a lower volume of fluid (3 L compared to the traditional 4 L) than most other PEG products. HalfLytely is an FDA-approved 2-L PEG product, but it must be taken with bisacodyl.

Last year, a Medical Letter article reviewing colonoscopy preparations warned that oral sodium phosphate preparations, such as Fleet Phospho-Soda solution and Visicol tablets, could cause significant electrolyte disturbances and, rarely, renal failure (Med Lett Drugs Ther 2005; 47:53). A subsequent report documented acute phosphate nephropathy and renal failure in 21 patients who had used sodium phosphate before colonoscopy (GS Markowitz et al. J Am Soc Nephrol 2005; 16:3389). Seventeen of these patients were women and 14 were taking an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). The FDA recently issued an alert advising against use of oral sodium phosphate in patients with kidney disease or uncorrected electrolyte abnormalities and urges caution in patients taking drugs that may affect renal function such as diuretics, NSAIDs, ACE inhibitors or ARBs.

Since the publication of our article on colonoscopy preparations,1 which compared polyethylene glycol electrolyte solutions (GoLytely, and others) with sodium phosphate (Fleet Phospho-Soda, and others), some readers have told us that we should have included a combination of a magnesium citrate solution with bisacodyl tablets (Evac-QKwik, and others) as an alternative. In one study, such a preparation offered better cleansing and patient tolerance than a sodium phosphate regimen.2

1. Colonoscopy preparations. Med Lett Drugs Ther 2005; 47:53.

2. M Delegge and R Kaplan. Efficacy of bowel preparation with the use of a prepackaged, low fibre diet with a low sodium, magnesium citrate cathartic vs. a clear liquid diet with a standard sodium phosphate cathartic. Aliment Pharmacol Ther 2005; 21:1491.