• efficacy will be measured and graded using video-taped record of each colonoscopy for cleansing in a 0 - 4 grade scale for each of the predefined colon areas by an endoscopist.
  
• Grades A or B means a good or correct preparation and are considered as a success whilst C or D are considered as a failed preparation.
  

• evaluation of the preparation quality using a visual analogue scale
  
• recording adverse events and clinical tolerance
  
• patient satisfaction
  

Multicentric (15 centres), prospective, randomised, single-blinded phase III pivotal study in patients undergoing a colonoscopy. Gut cleansing will be performed using 2 litres of NRL994 gut lavage solution with 1 litre (or more) of extra clear liquids or 2 x 45 ml of a sodium phosphate solution plus 2 litres (or more) of extra clear liquids the day before colonoscopy. Patients requiring a morning colonoscopy who fulfil the inclusion criteria, will be randomised. One of the two tested products will be delivered by a pharmacist, blindly from the gastroenterologist. The assigned product will be taken the day before the coloscopy according to the information leaflet. Efficacy of the two tested preparations will be measured on video-tape record of each colonoscopy by a final grading i.e. "the overall quality of colonoscopy prep" by an gastroenterologist expert. A standardised patient questionnaire administered by a nurse on the morning before colonoscopy will assess clinical tolerance and acceptability (satisfaction) of the prep. A baseline blood sampling will be withdrew before intake of the preparation and one more blood sample will be performed after the intake on the morning, before the coloscopy.

After the coloscopy, as the gastroenterologist gives the result of the coloscopy , a last visit is performed.