This study compares the effectiveness and stability of intestinal tablet (OST), an oral sulfate table (OST), developed in the form of pills, with 2L-PEG/Asc for examinees aged 70 or older who are scheduled for colonoscopy.

This study is comparison for efficacy and safety of bowel preparation between oral sulfate table and 2L-polyethylene glycol/ascorbate in elderly: multicenter, prospective, investigator single-blinded, randomized study. A total of 256 subjects will participate to this study and be assigned to the test group or the control group. The subject will administer the first dose of assigned investigational product in the evening prior to the scheduled colonoscopy. Subject will take the second dose early in the morning of the colonoscopy.

Inclusion Criteria:

• age over 70
• Patients who is scheduled a colonoscopy
• Patients who is informed and give a consent in voluntary

Exclusion Criteria:

• History of colectomy
• Patients over American Society of Anesthesiology class III
• Patients who has difficulty swallowing
• In the case of abnormal findings requiring treatment in the basic blood test
• Patients with uncontrollable chronic diseases
• Patients suspected of having Paralytic ileus or intestinal obstruction.
• Patients who complains of alarm sign (severe abdominal pain, weight loss, anemia, gastrointestinal bleeding, etc.)
• Patients who has a history of drug abuse and addiction
• Patients who for any reason, are deemed by the Investigator to be inappropriate for this study