The purpose of this study is to compare the safety and efficacy of BLI4900 bowel preparation to an FDA-approved control as 2-day, split-dose bowel preparations prior to colonoscopy in adult patients.

Inclusion Criteria:

• Male or female outpatients who are undergoing colonoscopy for a routinely accepted indication.
• 18 to 85 years of age (inclusive)
• If female, and of child-bearing potential, is using an acceptable form of birth control.
• Negative serum pregnancy test at screening, if applicable
• In the Investigator's judgment, subject is mentally competent to provide informed consent to participate in the study

Exclusion Criteria:

• Subjects with known or suspected ileus, gastrointestinal obstruction, gastroparesis, gastric retention, bowel perforation, toxic colitis or megacolon.
• Subjects with inflammatory bowel disease who have a history of any bowel resection (small intestine or colon), suspected active inflammation, or symptoms suggestive of obstruction or known bowel stricture.
• Subjects who had previous significant gastrointestinal surgeries.
• Subjects who have regularly used laxatives or colon motility altering drugs in the last month (i.e. more than 2-3 times per week) and/or laxative use within 72 hours prior to administration of the preparation
• Subjects with uncontrolled pre-existing electrolyte abnormalities, or those with clinically significant electrolyte abnormalities based on Visit 1 laboratory results.
• Subjects taking diuretics, anti-hypertensive medications, including angiotensin converting enzyme (ACE) inhibitors and Angiotensin II receptor blockers (ARBs), or chronic NSAIDs, that have not been stable for 30 days.
• Subjects with uncontrolled hypertension.
• Subjects taking antibiotics within 7 days of colonoscopy.
• Subjects with severe renal, hepatic or cardiac insufficiency.
• Subjects with an abnormal and clinically significant physical examination or ECG finding at Visit 1.
• Subjects undergoing insulin therapy for any indication.
• Subjects with impaired consciousness that predisposes them to pulmonary aspiration.
• Subjects undergoing colonoscopy for foreign body removal and/or decompression.
• Subjects taking tricyclic antidepressants.
• Subjects using drugs of abuse, including abused prescription medications.
• Subjects who are withdrawing from alcohol or benzodiazepines.