title: Sodium phosphate preparation for colonoscopy: onset and duration of bowel activity.
abstract: BACKGROUND
  Two doses of sodium phosphate are recommended for colonic cleansing before colonoscopy. Patients need information about the onset and duration of activity of the preparation. This study was designed to develop practical prescribing information to patients to reduce anxiety concerning bowel accidents.
  
  
  METHODS
  Two hundred patients were requested to take a liquid diet the day before colonoscopy, to take 45 mL sodium phosphate with water or juice the evening before and the morning of the procedure, and to complete a questionnaire.
  
  
  RESULTS
  Bowel activity began 1.7 hours (range 0.5 to 13) after the first dose and continued for 4.6 (1 to 14) hours. For the second dose the time to onset was 0.7 hours (0.25 to 4), and bowel activity continued for 2.9 hours (0.5 to 6.5). Bowel activity was completed 4 hours after ingestion of the second dose in 83% of patients and within 5 hours in 87%. Three of 200 patients reported the need for bowel evacuation during transit.
  
  
  CONCLUSIONS
  The activity from the second dose of sodium phosphate starts and ends sooner than that from the first dose. When advising patients on when to take the second dose of sodium phosphate, 4 hours for most and 5 hours for those with long commutes, should provide adequate time for almost all patients to avoid bowel activity during travel.
authors.affiliation: Division of Gastroenterology, Department of Medicine, Mount Sinai Medical Center, New York, New York, USA.
authors.forename: T B
authors.initials: TB
authors.lastname: Linden
authors.forename: J D
authors.initials: JD
authors.lastname: Waye
mesh_terms: D002400:Cathartics; D003106:Colon / Q000187:drug effects; D003113:Colonoscopy; D004334:Drug Administration Schedule; D005769:Gastrointestinal Motility / Q000187:drug effects*; D005772:Gastrointestinal Transit / Q000187:drug effects*; D006801:Humans; D010710:Phosphates / Q000008:administration & dosage* / Q000009:adverse effects; D007507:Therapeutic Irrigation
chemical_list: D002400:Cathartics; D010710:Phosphates; C018279:sodium phosphate