Double-blind dose-finding study of olsalazine versus sulphasalazine as maintenance therapy for ulcerative colitis

To determine the therapeutic efficacy and safety of three doses of olsalazine compared with the standard dose of sulphasalazine. Randomized double-blind multicentre 6-month study comparing three doses of olsalazine (0.5, 1.25 and 2.0 g daily) and sulphasalazine 2.0 g daily for maintaining remission in patients with ulcerative colitis. Public hospitals and private practices in Germany, Austria and Switzerland. A total of 162 patients with ulcerative colitis in remission. According to intention-to-treat analysis, the failure rates of the different treatment groups were not significantly different (36, 49 and 24% for 0.5, 1.25 and 2.0 g olsalazine daily and 32% for 2.0 g sulphasalazine daily). Olsalazine and sulphasalazine showed a tendency towards lower failure rates in extended (28%) than in distal disease (44%). The withdrawal rate due to adverse effects was 4%, the most frequent single event being diarrhoea (2.5, 5.2 and 11.7% for 0.5, 1.25 and 2.0 g olsalazine daily and 0% for sulphasalazine daily). This study found no significant differences between the therapeutic efficacy or safety of 0.5-2.0 g olsalazine daily. Because of its sulpha-free formulation olsalazine may, however, be preferred to sulphasalazine.