The aim of this study was to investigate the safety and efficacy of SPD476 2.4 g/day given twice daily ([BID] ie 1.2 g/day BID) and SPD476 4.8g/day given QD compared to placebo in subjects with acute, mild to moderate ulcerative colitis.

Inclusion Criteria:

• newly diagnosed or diagnosis of relapsing (relapsed <= 6 weeks to baseline) mild to moderate ulcerative colitis
• women not of childbearing potential or WOCP who agreed to use an effective contraceptive method

Exclusion Criteria:

• severe ulcerative colitis or relapsed for > 6 weeks prior to baseline
• subjects who had relapsed on maintenance therapy with doses of mesalazine > 2.0 g/day
• subjects with Crohn's disease, proctitis, bleeding disorders or active peptic ulcer disease
• subjects with asthma if they were known to be mesalazine-sensitive
• subjects who were at immediate or significant risk of toxic megacolon
• subjects who had previous resective colonic surgery
• subjects who had moderate or severe renal impairment