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Ascorbic Acid-Based Prep Improves Bowel Cleansing, Increases Small Adenoma Detection Rate During Colonoscopy: Presented at ACG

By Bruce Sylvester

SAN DIEGO -- October 27, 2009 -- Treatment with an ascorbic acid-based bowel prep dosed over 2 days achieves "excellent" colon cleansing and is associated with a 2-fold increase in detection of small adenomas, researchers reported here at the American College of Gastroenterology (ACG) 74th Annual Scientific Meeting.

"The findings of this study suggest a higher rate of adenoma detection is associated with an excellent bowel preparation compared with a good bowel preparation," said Lawrence Cohen, MD, Mount Sinai School of Medicine, New York, New York.

Researchers enrolled 107 patients into the study to compare the extent of bowel cleansing attained with two 2-L polyethylene glycol (PEG) formulations: one combines PEG plus 2 bisacodyl delayed-release tablets (PEG+Bis [HalfLytely]) while the other combines PEG with ascorbic acid and sodium ascorbate (PEG+Asc [MoviPrep]). The PEG+Bis formulation involves taking the 2 bisacodyl tablets the day before colonoscopy, then, no more than 6 hours later, consuming 2 litres of prep over 80 minutes. The PEG+Asc group consumed 1.5 litres the evening before the procedure and another 1.5 litres 6 hours before the procedure.

The quality of the colon cleansing, both overall and ascending colon, was rated by a blinded endoscopist using a validated 4-point scale, with 1 being "excellent" and 4 being "poor." Patients (n = 52) randomised to treatment with PEG+Asc attained an overall colon cleansing score of 1.40; the overall colon cleansing score of patients (n = 55) randomised to PEG+Bis was 1.75. Dr. Cohen said the difference between the scores achieved statistical significance (P = .003).

In addition, "excellent" bowel cleansing was recorded in 69.2% of patients who received the ascorbic acid and sodium ascorbate bowel preparation versus 38.2% of those receiving the bisacodyl delayed-release tablets; "good" bowel cleansing was recorded in 23.1% and 50.9%, respectively (P = .01).

Dr. Cohen added that the difference in bowel cleansing impacted the number of adenomas detected. The size, morphology, and location of each polyp were documented by a blinded research assistant. Twenty (39%) patients in the PEG+Asc group were found to have at least 1 adenoma compared with 11 (20%) patients in the PEG+Bis group (P = .04).

Almost all of that difference came in detection of polyps <10 mm. Colonoscopy revealed 17 of these smaller polyps in patients receiving PEG+Asc -- 33% of the total number of patients using that preparation. In patients who were taking PEG+Bis, doctors found 7 small adenomas -- representing 13% of the patients (P = .04).

"Polyethylene glycol with ascorbic acid and sodium ascorbate was superior to polyethylene glycol with bisacodyl delayed-release tablets as a bowel cleansing agent for both overall and ascending colon preparation," Dr. Cohen said at his October 25 poster presentation. "Patient tolerability was comparable for the 2 treatment groups."

The research was supported by Salix Pharmaceuticals.

[Presentation title: Is a Good Colonoscopy Bowel Prep Good Enough? Adenoma Detection Rates From a Randomization Study of Two Colon Cleansing Formulations. Abstract 412]

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