The aetiology of the chronic inflammatory bowel diseases - Crohn's disease and ulcerative colitis - is still enigmatic. The therapeutic approach has therefore traditionally focused on anti-inflammatory principles, including corticosteroids and aminosalicylates. Since a significant proportion of patients is steroid-dependent or refractory and because of the problematic side-effects of long-term systemic steroids, active immunosuppression has gained acceptance in the field.
The classical immunosuppressants azathioprine and 6-mercaptopurine have long been evidence-based in IBD, but...