Efficacy and tolerability of split-dose PEG compared with split-dose aqueous sodium phosphate for outpatient colonoscopy: a randomized, controlled trial

Dig Dis Sci. 2011 Oct;56(10):2963-71. doi: 10.1007/s10620-011-1772-1. Epub 2011 Jun 9.


Background and aims: Adequate bowel cleansing is essential for a high-quality, effective, and safe colonoscopy. The aims of this study were to compare the efficacy and tolerability of split-dose polyethylene glycol with aqueous sodium phosphate for outpatients who underwent scheduled colonoscopy.

Methods: In this prospective trial, 207 outpatients (aged between 18 and 65 years, with normal renal function, at low risk for renal damage) were randomized to receive split-dose preparation of PEG (2 L/2 L) (N = 103) or NaP (45 mL/45 mL, 12 h apart) (N = 104) without strict diet restriction the day before colonoscopy. The bowel cleansing efficacy of preparations was rated according to the Ottawa scale and the patient tolerability was assessed using a patient questionnaire.

Results: There was no significant difference between the two groups for the mean total score using the Ottawa bowel preparation scale (P = 0.181). Significantly greater residual colonic fluid was observed in the split-dose PEG group (1.24 ± 0.49) than in the NaP group (1.04 ± 0.53) (P = 0.007). Patient compliance, preference, and acceptance of a two preparation regimen were similar with no significant differences (P = 0.095, P = 0.280 and P = 0.408, respectively). The overall incidence of adverse events was not significantly different between the two groups; however, the split-dose PEG group tended to have fewer adverse events (52/103 [50.5%], 66/104 [63.5%], P = 0.059) and had significantly less nausea and vomiting (P = 0.036).

Conclusions: Split-dose PEG, compared with split-dose NaP, is associated with more residual colonic fluid, but produces equivalent colon cleansing efficacy and results in less nausea and vomiting, which might improve patient tolerability (clinical trial registration number NCT01229800).

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Cathartics / adverse effects
  • Cathartics / therapeutic use*
  • Colonoscopy / methods*
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Nausea / epidemiology
  • Outpatients*
  • Patient Compliance
  • Patient Satisfaction
  • Phosphates / adverse effects
  • Phosphates / therapeutic use*
  • Polyethylene Glycols / adverse effects
  • Polyethylene Glycols / therapeutic use*
  • Prospective Studies
  • Treatment Outcome
  • Vomiting / epidemiology


  • Cathartics
  • Phosphates
  • Polyethylene Glycols
  • sodium phosphate

Associated data

  • ClinicalTrials.gov/NCT01229800