The primary objective of this study is to compare the efficacy of administration routine bowel cleansing medication (Bowklean) for the Bowel Preparation at Different Times Prior Colonoscopy in the morning or in the afternoon.

Sodium picosulfate/magnesium citrate (SPMC) is a small-volume bowel cleansing agent with similar efficacy and better tolerability than polyethylene glycol. However, there was limited data about the bowel cleansing efficacy of SPMC in comparing the same-day and split-dose preparation for afternoon colonoscopy.

This randomized, single-center, endoscopist-blinded, non-inferior study compared same-day (101 subjects) and split-dose (96 subjects) preparation with SPMC for afternoon colonoscopy. One additional prospective observation group of 100 subjects receiving colonoscopy in the morning was included as an observation group to compare bowel preparation in morning and afternoon colonoscopy. Efficacy of bowel cleansing was evaluated by the Aronchick Scale, Ottawa Bowel Preparation Scale (OBPS), Boston Bowel Preparation Scale (BBPS), and the Bubble Scale (TBS).

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