This study will check the reproducibility of the results reported in trials with budesonide in patients with collagenous colitis. Efficacy of mesalazine was never tested in collagenous colitis by placebo-controlled trials. This trial will check the superiority of mesalazine over placebo using the common clinical symptom of collagenous colitis, which is chronic or recurrent non-bloody, watery diarrhea.
The purpose of this study is to determine whether budesonide or mesalazine is more active in the treatment of collagenous colitis.