Objective: To determine the therapeutic efficacy and safety of three doses of olsalazine compared with the standard dose of sulphasalazine.
Design: 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.
Setting: Public hospitals and private practices in Germany, Austria and Switzerland.
Patients: A total of 162 patients with ulcerative colitis in remission.
Results: 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).
Conclusion: 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.