Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trial

Am J Gastroenterol. 2010 Mar;105(3):675-81. doi: 10.1038/ajg.2009.598. Epub 2009 Oct 20.


Objectives: Patients' compliance with and tolerance of large-volume polyethylene glycol electrolyte solution (PEG-ES) have prompted continuous investigation with alternative forms of cleansing. High-dose senna is superior to PEG-ES for the quality of bowel cleansing, patient compliance, and tolerance, but its acceptance may be influenced by the incidence of abdominal pain. We hypothesized that a combination of half doses of PEG-ES and senna could minimize the incidence of abdominal pain without affecting the quality of bowel preparation.

Methods: This randomized, investigator-blinded trial has been conducted on consecutive outpatients scheduled for elective colonoscopy at a single community-based hospital. Patients were randomly assigned to receive either 12 tablets of 12 mg senna and 2 l of PEG-ES (half-dose group, HDG) or 24 tablets of senna divided in two doses (senna group, SG) the day before colonoscopy. The main outcome measures were the quality of colon cleansing (Aronchick scoring scale) and the incidence of preparation-related abdominal pain. Secondary outcome measures were patients' compliance with the cleansing regimen, overall tolerability, prevalence of predefined side effects, and quality of right colon cleansing.

Results: A total of 296 patients were enrolled (HDG=151 and SG=145). Overall cleansing was excellent to good in 90.1 and 88.3% patients in HDG and SG, respectively (P=0.62). Preparation-related moderate-to-severe abdominal pain was reported by 6% patients in HDG and 15.2% in SG (P=0.009). No significant differences were observed for secondary outcomes.

Conclusions: The regimen combining half doses of PEG-ES and senna provides high-quality bowel preparation and acceptable patient tolerance, with less abdominal pain compared with high-dose senna.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Abdominal Pain / chemically induced
  • Abdominal Pain / epidemiology
  • Abdominal Pain / prevention & control*
  • Administration, Oral
  • Cathartics / administration & dosage*
  • Colonoscopy*
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Patient Compliance
  • Polyethylene Glycols / administration & dosage*
  • Senna Extract / administration & dosage*
  • Statistics, Nonparametric
  • Surface-Active Agents / administration & dosage*
  • Therapeutic Irrigation / methods
  • Treatment Outcome


  • Cathartics
  • Surface-Active Agents
  • Polyethylene Glycols
  • Senna Extract