Azathioprine is used as an immunosuppressant antimetabolite either alone or, more commonly, in combination with other agents (usually corticosteroids) and procedures which influence the immune response. Therapeutic effect may be evident only after weeks or months and can include a steroid-sparing effect, thereby reducing the toxicity associated with high dosage and prolonged usage of corticosteroids. Azathioprine, in combination with corticosteroids and/or other immunosuppressive agents and procedures, is indicated to enhance the survival of organ transplants, such as renal transplants, cardiac transplants, and hepatic transplants. It also reduces the corticosteroid requirements of renal transplant recipients. Azathioprine is indicated for the treatment of moderate to severe inflammatory bowel disease (IBD) (Crohn's disease or ulcerative colitis) in patients in whom corticosteroid therapy is required, in patients who cannot tolerate corticosteroid therapy, or in patients whose disease is refractory to other standard first line therapy. Azathioprine, either alone or more usually in combination with corticosteroids and/or other medicinal products and procedures, has been used with clinical benefit (which may include reduction of dosage or discontinuation of corticosteroids) in a proportion of patients suffering from the following: • severe rheumatoid arthritis; • systemic lupus erythematosus; • dermatomyositis and polymyositis; • auto-immune chronic active hepatitis; • pemphigus vulgaris; • polyarteritis nodosa; • auto-immune haemolytic anaemia; • chronic refractory idiopathic thrombocytopenic purpura.
