Azathioprine in ulcerative colitis: Why, when, how and how long to use it

Ulcerative colitis (UC) is a lifelong, immune‐mediated inflammatory condition of the colonic mucosa characterized by a relapsing and remitting course. The mainstay of treatment used to be the 5‐aminosalicylates (5‐ASA) and corticosteroids. Nevertheless, some patients are unable to discontinue or reduce the steroid dosage and are exposed to a number of side effects. The efficacy of thiopurines is well proven in inflammatory bowel disease (IBD); azathioprine (AZA) is considered the first‐line immunosuppressant with a steroid‐sparing effect in UC patients with steroid dependence or resistance. Success rates of 70% occur in induction therapy with AZA and 6‐mercaptopurine (MP) in UC with a number‐needed‐to‐treat (NNT) to avoid recurrence (with AZA/MP, as compared with placebo) of 5 and absolute risk of reduction of 23%. Thus, AZA and MP are an effective therapeutic option in inducing and maintaining remission for UC patients who failed to improve or who do not tolerate 5‐ASA or corticosteroids. Drug Dev Res 72:733–738, 2011. © 2011 Wiley Periodicals, Inc.