Bowel preparation is a major determinant of colonoscopy and colorectal surgery. Polyethylene glycol electrolyte solutions (PEG-E) are the most commonly used laxatives in China. However, a significant number of patients, especially those constipated patients, failed colonoscopies due to poor bowel cleaning. Inadequate preparation may also lead to missed colonic lesions. The study is based on the hypothesis: itopride hydrochloride, a prokinetic agent, its dual role as dopamine D2 receptor antagonism and acetylcho-linesterase inhibition make it an appropriate adjuvant for bowel preparation. It was reported to promote colonic peristalsis, shorten colonic transit time and accelerate propulsion of colonic luminal contents through inhibition of M3 receptor and dopamine D2 receptors in vitro and in vivo. So this study is to determine the efficacy, tolerance and safety of high dose of itopride, when given in different times before administration of PEG-E, for colonic preparation in patients with chronic constipation.

Colonoscopy is a reliable procedure for the investigation of colonic and distal terminal ileum disease. The diagnostic accuracy of colonoscopy is dependent on visualization of the colonic mucosa; hence an appropriate bowel preparation is essential for the examination. Despite multiple lavage were used throughout the years, the suboptimal cleaning level have been reported vary from 10% to more than 20% and up to one-third of incomplete or failed colonoscopies can be ascribed to poor bowel preparation. So it is important for us to search a new regimen for bowel preparation.

Inclusion Criteria:

• Patients suspected colonic disease and suffered from chronic constipation were referred for colonoscopy and enrolled in the study. Chronic constipation was diagnosed on the basis of Rome III criteria.Suspected colonic disease was defined as:

  • recent change of bowel habits;
  • obscure GI bleeding (hemafecia, melena or positive fecal occult blood test);
  • obscure abdominal pain;
  • weight loss;
  • positive findings in the colon on GI imaging;
  • serological test referred to colorectal cancer such as CEA elevated obviously;
  • family history of colorectal cancer or adenomatous polyps.

Exclusion Criteria:

• usage of prokinetic agents such as itopride, mosapride within 4 weeks and tricyclic antidepressants 8 weeks prior to entering the protocol;
• known allergies or other contraindication to PEG or itopride;
• a history of abdominal surgery or bowel obstruction;
• pregnant or lactating;
• conditions associated with severe cardiac, hepatic, or renal impairment.