4-Amino Salicylic Acid (4-ASA)

Enemas of 4-amino-salicylic acid (4-ASA) have been compared with placebo enemas in a double-blind study for the treatment of distal ulcerative colitis of mild to moderate severity. 30 patients were randomised to receive enemas containing 1 g of 4-ASA or placebo, and 22 to receive 2-gram enemas of 4-ASA or placebo. For each dose of 4-ASA there was clinical and sigmoidoscopic improvement, which reached significance when all patients receiving 4-ASA enemas were compared with those receiving placebo enemas. There was also a trend towards histological improvement, but this failed to reach the level of significance. These findings suggest that 4-ASA may provide a stable, inexpensive alternative to 5-ASA for the topical treatment of ulcerative colitis or for linking to carrier molecules for release in the colon.