Azathioprine, sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used for the treatment of rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus erythematosus; and in kidney transplants to prevent rejection. It is listed by the International Agency for Research on Cancer as a group 1 human carcinogen. It is taken by mouth or injected into a vein.
Common side effects include bone-marrow suppression and vomiting. Bone-marrow suppression is especially common in people with a genetic deficiency of the enzyme thiopurine S-methyltransferase. Other serious risk factors include an increased risk of certain cancers. Use during pregnancy may result in harm to the baby. Azathioprine is in the purine analogue and antimetabolite family of medications. It works via 6-thioguanine to disrupt the making of RNA and DNA by cells.
Azathioprine was first made in 1957. It is on the World Health Organization's List of Essential Medicines. In 2018, it was the 358th most commonly prescribed medication in the United States, with more than 800,000 prescriptions.
Azathioprine is used alone or in combination with other immunosuppressive therapy to prevent rejection following organ transplantation, and to treat an array of autoimmune diseases, including rheumatoid arthritis, pemphigus, systemic lupus erythematosus, Behçet's disease, and other forms of vasculitis, autoimmune hepatitis, atopic dermatitis, myasthenia gravis, neuromyelitis optica (Devic's disease), restrictive lung disease, and others. It is also an important therapy and steroid-sparing agent for inflammatory bowel disease (such as Crohn's disease and ulcerative colitis) and for multiple sclerosis.
In the United States, it is approved by the Food and Drug Administration for use in kidney transplantation from human donors, and for rheumatoid arthritis.
Azathioprine is used to prevent rejections of kidney or liver allografts, usually in conjunction with other therapies including corticosteroids, other immunosuppressants, and local radiation therapy.