Effects of the addition of high-dose vitamin C to polyethylene glycol solution for colonic cleansing: A pilot study in healthy volunteers.

BACKGROUND

Polyethylene glycol (PEG) solutions, with or without osmotic agents, are used to empty the large intestine before procedures such as colonoscopy or colonic surgery. Data concerning the effectiveness of vitamin C as an ingredient in colonic preparations are scant.

OBJECTIVE

The aim of this article was to assess the effectiveness, acceptability, and tolerability of 6 preparations of a standard PEG electrolyte solution containing different doses of PEG, vitamin C (as an osmotic agent), and sodium sulfate in colonic cleansing.

METHODS

This double-blind, randomized, 2-period crossover study was conducted at the Lariboisière Hospital, Paris, France. Healthy adult volunteers were randomly assigned to receive 2 of 6 colonic cleansing preparations, each containing different doses of PEG (100 or 125 g/L), vitamin C (0, 5, or 10 g/L, in the form of sodium ascorbate, ascorbic acid, or a mixture of both), and sodium sulfate (5 or 7.5 g/L), diluted in water to a volume of 2 L. Study drug administration was separated by a washout period of 7 to 15 days, after which the volunteers received an alternate preparation. Stools were collected for 10 hours after the start of solution ingestion. The primary efficacy end point was stool volume. Secondary end points included acceptability of taste, assessed using a 100-mm visual analog scale (VAS) (0 = excellent to 100 = execrable), taste criteria (saltiness, acidity, and sweetness, assessed on a 4-point Likert-type scale [0 = very pleasant to 3 = intolerable]) and tolerability (clinical effects [changes in body weight, blood pressure, heart rate, and nausea and vomiting] and biologic effects [changes in serum electrolytes, creatinine, hematocrit, and ascorbic acid]).

RESULTS

Thirty volunteers (15 men, 15 women; mean [SD] age, 29.8 [8.2] years [range, 20-45 years]) were enrolled and completed the study. Mean (SD) stool volume obtained with preparations containing 10 g/L of vitamin C did not differ significantly from the volume obtained without vitamin C (2.54 [0.54] L vs 1.93 [0.62] L; 95% CI, -0.13 to 1.47). Mean (SD) VAS scores for acceptability of taste ranged from 54.4 (25.0) (preparation E) to 74.4 (20.1) (preparation C) (P = 0.03 preparation E vs all other preparations). The only significant difference in taste criteria was in acidity, with preparation A being the least acidic according to patients' ratings on the VAS (1.4 [0.7] vs 1.8 [0.4] [mean of the other 5 preparations combined]; P = 0.04 preparation A vs all other preparations). Mild dehydration occurred in 6 subjects (1 for each preparation). No clinical or biological adverse effects were found.

CONCLUSIONS

In this study of 6 colonic cleansing preparations in healthy volunteers, the use of high-dose vitamin C as an osmotic agent in addition to PEG did not significantly increase stool output. All 6 preparations were well tolerated.