Efficacy and Safety of Asacol™ 4.8 g/Day (800 mg Tablets) for the Treatment of Active Ulcerative Colitis

Inclusion Criteria: (1) Male or non-pregnant, non-lactating females, 18 years of age or older. (2) Documented diagnosis of UC with disease extending at least 15 cm from the anal verge. (3) Active UC defined by: (a) modified UC-DAI score of 4-10 with (b) sigmoidoscopy component score ≥ 2 and (c) rectal bleeding component score ≥ 1 (4) Ability of subject to participate fully in all aspects of this clinical trial. (5) Written informed consent must be obtained and documented. Exclusion Criteria: 1. Severe UC defined by the following criteria: ³6 bloody stools daily with one or more of the following: 1. oral temperature \> 37.8°C or \> 100.0°F 2. pulse \> 90/min 3. hemoglobin \< 10 g/dL 2. Previously failed treatment with a mesalazine dose of \> 2.0 g/day. 3. Current relapse lasting \> 6 weeks in the opinion of the investigator. 4. Treatment with 5-ASA at a dose of \>2.0g/day within 1 week prior to randomisation 5. Treatment with systemic or rectal steroids within 4 weeks prior to randomization. 6. Treatment with immunosuppressants within 6 weeks prior to randomization. 7. Treatment with infliximab or other biologics within 3 months prior to randomization. 8. Treatment with systemic antibiotics for UC within 7 days prior to randomization. 9. Treatment with probiotics within 7 days prior to randomization. 10. Treatment with anti-diarrheals within 7 days prior to randomization. 11. Treatment with nicotine patch within 7 days prior to randomization. 12. Received any investigational drug within 30 days prior to randomization. 13. History of colectomy or partial colectomy. 14. History of definite dysplasia in colonic biopsies. 15. Crohn's disease. 16. Known bleeding disorders. 17. Immediate or significant risk of toxic megacolon. 18. Hypersensitivity to salicylates, aspirin, sulfasalazine or 5-ASA. 19. Serum creatinine \> 1.5 times the upper limit of the normal range. 20. AST, ALT, total bilirubin or alkaline phosphatase \> 2 times the upper limit of the normal range. 21. Serious underlying disease other than UC which in the opinion of the investigator may interfere with the subject's ability to participate fully in the study. 22. History of alcohol or drug abuse which in the opinion of the investigator may interfere with the subject's ability to comply with the study procedures. 23. Stools positive for clostridium difficile. 24. Pregnant or lactating women. 25. Prior enrolment in the current study and had received study treatment.