Therapy of Inflammatory Bowel Disease using New 5-ASA Compounds: An Introduction

Strong evidence has been accumulating that mesalazine (5-aminosalicylic acid, 5-ASA) represents the therapeutic moiety of the standarddrug sulphasalazine. Since the active metabolite avoids the toxic potential ofsulphapyridine, this perception has initiated new therapeutic approaches, forexample, two 5-ASA molecules have been coupled to form another prodrug(olsalazine) which again depends on a proper cleavage of the azobond by bacteriain the colon A more direct way has been applied successfully by administering5-ASA itself in special galenic formulation (suppositories, enemas, controlled releasepreparations) to provide enough active material at the proposed sites of action inthe terminal ileum and/or colon. One major advantage of all 5-ASA compounds,compared to sulphasalazine, is their 10-fold lower potential (incidence) for inducingallergic reactions or causing intolerance. Aside from rare hypersensitivity reactions,5-ASA can cause nausea. vomiting, headache and gastrointestinal disturbancesin 1 to 5% of patients. However, the new azocompound olsalazine induceddiarrhea or loose stool in at least 10 to 15% of the treated patients which mightlimit its use in inflammatory bowel disease (IBD). In conclusion, the ‘old’ metabolite5-ASA, in a ‘new’ design, offers an effective and very safe choice for the treatment of IBD