Clinical Trial on Bowel Preparation Comparing Mannitol 100g to Plenvu Both in a Same Day Regimen (CLEARWAY)

Inclusion Criteria: 1. Ability of subject to consent and provide signed written informed consent. 2. Age ≥ 18 years. 3. Males and females scheduled for elective colonoscopy performed according to ESGE guidelines. 4. Subjects willing and able to complete the entire study and to comply with instructions. Exclusion Criteria: 1. Pregnancy or breast feeding. Females of childbearing potential must have a negative pregnancy test at Visit 2 and practice highly effective methods of birth control throughout the study period, according to the CTCG "Recommendations related to contraception and pregnancy testing in clinical trials" v 1.2\* (unless postmenopausal or surgically sterile, or whose sole sexual partner had a successful vasectomy). 2. Severe acute and chronically active inflammatory bowel disease; subjects in clinical remission (Crohn's Disease Activity Index - CDAI \< 150 for Crohn Disease (Best et al. 1976) and Partial Mayo Score ≤ 2 for Ulcerative Colitis (Schroeder et al. 1987)) are allowed. 3. Severe renal failure: eGFR \< 30 ml/min/1.73 m2 estimated by simplified MDRD equation. 4. Severe heart failure: New York Heart Association (NYHA) Class III-IV. 5. Severe anaemia (Hb ≤ 8 g/dl). 6. Chronic liver disease Child-Pugh class B or C. 7. Electrolyte disturbances (baseline values of Na2+, Cl-, K+ out of normal ranges). 8. Clinically significant alterations of baseline haemato-chemical parameters. 9. Recent (\< 6 months) symptomatic acute ischemic heart disease. 10. History of significant gastrointestinal surgeries, including colon resection, sub-total colectomy, abdominoperineal resection, de-functioning colostomy or ileostomy, Hartmann's procedure and other surgeries involving the structure and function of the colon. 11. History of paralysis of the gut (ileus). 12. History of disorders of gastric emptying (e.g. gastroparesis, gastric retention, etc.). 13. History of phenylketonuria (due to presence of aspartame). 14. History of glucose-6-phosphate dehydrogenase deficiency (due to presence of ascorbate). 15. History of toxic megacolon. 16. Use within 24 hours prior to colonoscopy of laxatives, colon motility altering drugs and/or other substances (e.g., simethicone) that could affect bowel cleansing or visibility during colonoscopy. 17. Suspected bowel obstruction or perforation. 18. Indication for partial colonoscopy. 19. Subjects who received an investigational drug or therapy within 5 half-lives of the first visit. 20. Hypersensitivity to the active ingredients or to any of the excipients of the study drugs. 21. Underwater colonoscopy instead of standard gas insufflation.