The Colitis Once Daily Asacol Study

Study design * Multicentre, randomized, single-blind, comparator-controlled, parallel-armed study * One year follow-up, or until relapse (whichever shorter) * 40-60 UK centres Subject population * Ulcerative colitis in remission (sigmoidoscopy score of 0 or 1 with no symptoms of active disease, with no treatment for active colitis) for at least 4 weeks, and for no more than 2 years * Taking mesalazine or sulfasalazine prior to study entry * Patients excluded if they have Crohn's disease, symptoms of active colitis, have used corticosteroids, ciclosporin or oral/enema mesalazine in the past 4 weeks, are intolerant to mesalazine or Asacol, are pregnant or lactating, or have known HIV, hepatic disease, renal impairment or other serious medical or psychiatric illness * Sample size 250 * Gender: male or female * Ethnicity: no restriction * Age: over 18 Test Product Once daily group: Asacol® 2.4g daily given as three 800mg tablets orally qAM Three times daily group: Asacol® 2.4g daily given as one 800mg tablet orally three times daily Criteria for Evaluation: Primary Outcome Variable: Relapse rate over 1 year in the intention to treat population, with the study powered to detect non-inferiority of the once-daily regimen. Secondary Outcome Variables: assessment of superiority of the once-daily regimen, if non-inferiority is demonstrated; safety analysis; per protocol analysis of relapse rate; time course of relapse; medication compliance; changes in modified Baron sigmoidoscopy scores between trial entry and relapse/12 month; impact of various factors on relapse rate (time from last relapse at study entry, concomitant azathioprine or 6-mercaptopurine therapy; disease extent; disease duration; smoking status; age at diagnosis; previous dose of mesalazine; baseline calprotectin; baseline CRP level).