A mesalazine enema for ulcerative colitis.

Given by mouth, drugs based on 5-aminosalicylic acid (5-ASA) are often effective in inducing or maintaining remission in patients with ulcerative colitis. All of them depend on delaying the release of 5-ASA, so minimising its absorption in the small intestine and maximising delivery to the colon. With sulphasalazine (a chemical combination of 5-ASA and sulphapyridine) and olsalazine (a combination of two molecules of 5-ASA) cleavage of the azo bond by bacteria releases free 5-ASA in the colon. Oral formulations of mesalazine (the approved name for 5-ASA when given alone as a drug) use various physical mechanisms to release the 5-ASA gradually during transit through the gastrointestinal tract. Mesalazine can now be administered directly to the colon as an enema (Pentasa-Yamanouchi Pharma). How effective is this method of administering mesalazine and does it have a specific place in therapy?