Review article: the management of refractory Crohn's disease.

Refractoriness to conventional therapy is a common and intriguing problem in Crohn's disease patients. At the present time there is no agreement on its definition and several mechanisms are involved in its determination. Immunosuppressors, such as azathioprine (AZA), 6-mercaptopurine (6MP) and methotrexate (MTX) are effective drugs for controlling the inflammatory process and avoid chronic glucocorticosteroid treatment and its related side-effects. Recently, the introduction of tumour necrosis factor antibodies (infliximab) has dramatically changed the natural history of Crohn's disease and its therapeutic approach. Several studies have determined the efficacy, mechanisms and safety of infliximab. However, this molecular approach has also left several questions unanswered about the mechanisms of refractoriness, possible concomitant treatments and long-term safety and efficacy.