Balsalazide is a prodrug of mesalazine which has an inert carrier molecule instead of the sulfapyridine moiety of sulfasalazine. Balsalazide 6.75 g/day was more effective than mesalazine 2.4 g/day in at least 1 trial and as effective as sulfasalazine 3 g/day for inducing remission in patients with acute ulcerative colitis in 8- and 12-week trials. Moreover, complete symptom relief occurred more promptly with balsalizide 6.75 g/day than with mesalazine 2.4g/day. In long term studies, balsalazide 2 g/day was as effective as sulfasalazine 2 g/day and balsalazide 6 g/day was as effective as mesalazine 1.5 g/day, in maintaining remission in patients with ulcerative colitis. The tolerability profile of balsalazide is significantly better than that of sulfasalazine; 70% of sulfasalazine-intolerant patients were able to tolerate balsalazide.