Efficacy, Safety and Tolerability of Magnesium Sulfate With Low-volume Polyethylene Glycol for Colonoscopy Cleansing

Inclusion Criteria: * 18-75 years old, male or female * To undergo screening, surveillance and diagnostic colonoscopy * Signed written informed consent Exclusion Criteria: * Subjects with therapeutic colonoscopy for colorectal polyps * Subjects with confirmed or suspected gastrointestinal obstruction, gastric retention, gastroparesis, gastric emptying disorder, or acute gastrointestinal bleeding * Subjects with confirmed or suspected colorectal cancer, inflammatory bowel disease, toxic colitis, or toxic megacolon * Subjects with renal or liver dysfunction, congestive heart failure or rhabdomyolysis * Subjects with ascites, suspected electrolyte abnormalities, or uncorrected dehydration * Subjects with constipation (\<3 times a week, difficult defecation, dry stool, less amount) * Subjects with serious cardiac and cerebrovascular diseases,suffering from metabolic disease or endocrine disease * Subjects who had previously undergone colorectal resection * Women with positive pregnancy tests or pregnancy plans, and women in lactation or allergic to the investigational drugs and their ingredients * Subjects who are participating in other clinical trials or receiving special drugs * Subjects with any other conditions that the investigator considered inappropriate for inclusion