OD vs. TID Dosing With Mesalazine Granules in Active Ulcerative Colitis

Inclusion Criteria (main): * Active ulcerative colitis except proctitis, i.e. inflammation minimal 15cm ab ano, confirmed by endoscopy and histology * Established or new diagnosis * Disease activity at baseline: Clinical Activity Index (CAI) \>4 and Endoscopic Index (EI) \>= 4 Exclusion Criteria (main): * Crohn's disease * Toxic megacolon * Present or past colorectal cancer * Symptomatic gastrointestinal disease * Serious secondary disease(s) * Baseline stool positive for germs causing bowel disease * Immunosuppressants within 3 months and/or corticosteroids within 1 month prior to baseline * Current relapse occurred under maintenance treatment with \>2g/day mesalazine * Serum creatinine \>= 1.2x upper limit of normal (ULN) and creatinine clearance \< 60 ml/min per 1.73 m2 * Serum transaminase (ALT and/or AST), and/or alkaline phosphatase \>= 2x ULN