This is a single center, open-label, pilot study to determine the safety, efficacy, and patient preference of a split-dose regimen of Crystalline Lactulose for cleansing of the colon prior to colonoscopy. Safety will be assessed by the occurrence of any treatment emergent adverse events. Efficacy will be determined by the endoscopist's rating of the cleanliness of the colon and the incidence of treatment failure (insufficient evacuation of the bowel). Patient preference will be determined by the patient's responses on a patient questionnaire.