Budesonide Capsules vs. Mesalazine Granules vs. Placebo in Collagenous Colitis

Inclusion Criteria (main): * \> 4 watery/soft stools on at least 4 days in the week prior to baseline * \> 3 stools per day on average within the last 7 days prior to baseline * Symptoms (chronic watery diarrhea) for at least 3 months before baseline * Complete colonoscopy within the last 12 weeks before baseline * Histologically confirmed diagnosis of collagenous colitis Exclusion Criteria: * Evidence of infectious diarrhea * Celiac disease * Endoscopic-histologic findings, which may have caused diarrhea * History of partial colonic resection * Diarrhea as a result of the presence of other symptomatic organic disease of the gastrointestinal tract * Active colorectal cancer or a history of colorectal cancer * Severe co-morbidity substantially reducing life expectancy * Abnormal hepatic function or liver cirrhosis (ALT, AST or AP \>= 2 x ULN) * Abnormal renal function (Cystatin C \> ULN) * Active peptic ulcer disease, local intestinal infection * Asthma, diabetes mellitus, infection, osteoporosis, glaucoma, cataract, or cardiovascular disease if careful medical monitoring is not ensured * Hemorrhagic diathesis