The effect of topical N-acetyl-5-aminosalicylic acid in ulcerative colitis.

In a double-blind controlled therapeutic trial, retention enemas of N-acetyl-5-aminosalicylic acid (Ac-5-ASA) were compared with dummy enemas in the treatment of active ulcerative colitis. Forty patients were studied, each patient taking one test enema twice a day for 2 weeks. Seventeen of the patients had a mild clinical attack of the disease; the 23 others had sigmoidoscopic evidence of active inflammation although they were in clinical remission. Histological and sigmoidoscopic improvement were significantly commoner in the patients receiving the active treatment than in those taking the dummy preparation. Pronounced histological improvement was only seen in patients taking the Ac-5-ASA enemas. In those patients who had clinical attacks of ulcerative colitis at the start of the study, symptomatic improvement was commoner in the group treated with Ac-5-ASA enemas than in those who received placebo therapy. Ac-5-ASA resembles 5-aminosalicylic acid in its effect on the inflamed mucosa in ulcerative colitis. Further studies into other substituted salicylates may lead to the development of an effective oral agent that does not carry the side effects associated with the sulphapyridine moiety of sulphasalazine.