The purpose of this study to bowel cleansing evaluation of mixed two other type bowel preparation drug(PICOLIGHT plus COOLPREP, PICOLIGHT plus CLICOLON).

To evaluate mixed-drug bowel preparation methods for decreasing side effect and increasing compliance

Picolight + Coolprep [Day-Prior] Picolight + Clicolon [Day-Prior] Picolight + Coolprep [Split-Dose] Picolight + Clicolon [Split-Dose]

Inclusion Criteria:

• 20-65 years of age
• Elective colonoscopy of outpatients(consent to the study)

Exclusion Criteria:

• Active enteritis, enteric bleeding, obstruction
• Pregnant or lactating women
• Severe liver or renal insufficiency
• Allergic to any preparation components
• History of heart disease (ischemic heart disease, congestive heart failure, arrythmia)
• History of colorectal surgery
• History abdominal surgery within 6 month
• Toxic colitis or megacolon
• Nausea or vomiting
• Status emergent abdominal surgery (ex. acute appendicitis)
• Uncontrolled clinically significant pre-existing electrolyte disturbance
• Dehydration
• Phenylketonuria
• Glucose-6-phosphate dehydrogenase deficiency
• Ileus
• Suspicious hyperphosphatemia
• Acute phosphate nephropathy