Colonoscopy: Preparations For Patients Prescribed with 2L or 3L PEG (8AM to 2PM) Download PDF, 1.88MB, PDF Polyethylene Glycol Electrolyte Solution (PEG) is used to clean out the gastrointestinal tract (stomach and intestines). Bisacodyl is a drug (laxative) which stimulates the muscle in the intestines, in order to create bowel movements (pass motion).Read on to find out how to prepare for a colonoscopy for patients prescribed with 2 litres or 3 litres of PEG for a procedure from 8am to 2pm.You can also find out more about colonoscopy by scanning the QR code in the attached booklet, or click here. [Please download the PDF file if you are unable to view the image below.]