Different Dosing Time of Bowklean for the Bowel Preparation

Inclusion Criteria: 1. Subject is 20 and 99 years, inclusive. 2. Men or non-pregnant women who are scheduled for an elective colonoscopy. 3. Subjects should be willing, able to complete the entire procedure and to comply with study instructions. 4. Written informed consent obtained prior to study. Exclusion Criteria: 1. Patients who are not suitable for colonoscopy * Acute surgical abdominal conditions (e.g. acute obstruction or perforation, etc.) * Active (acute/exacerbation of/severe/uncontrolled) Inflammatory Bowel Disease (IBD) * Colon disease (history of colonic cancer, toxic megacolon, toxic colitis, idiopathic pseudo- obstruction, hypomotility syndrome) * Gastrointestinal disorder (active ulcer, outlet obstruction, gastric retention, gastroparesis, ileus) * Uncontrolled angina and/or Myocardial Infarction (MI) within last 3 months before randomization, Congestive Heart Failure (CHF), arrhythmia, cardiomyopathy or uncontrolled hypertension * Renal insufficiency 2. Any prior colorectal surgery * in the past 3 months, excluding appendectomy, hemorrhoid surgery or prior endoscopic procedures * History of upper gastrointestinal surgery (gastric resection, gastric banding, gastric by-pass) 3. Severe chronic constipation 4. Hypersensitivity to any ingredient in the study medication