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Immuno-suppressive Drugs

Azathioprine belongs to a group of immunosuppresive drugs which are used in veterinary medicine to treat various immune-mediated disorders. Some of the diseases related to overactive or improperly responding immune system include lupus erythematosus, lymphocytic-plasmacytic enteritis, rheumatoid arthritis, immune-mediated skin disease and hemolytic anemia. Many of the immuno-suppresive drugs work by interfering with one of the stages of the cell cycle by affecting cellular messengers.1


Azathioprine is an antimetabolite that inhibits both T-lymphocytes and B-lymphocytes to bring about immunosppression. Antimetabolites are chemically similar to naturally occurring metabolites, but differ enough to interfere with normal metabolic pathways. Azathioprine has fewer side effects than cyclophosphamide and some of the other immunosuppressants. It is often used in combination with prednisone and prednisolone (an adrenocortical steroid).1

Use of Azathioprine

Azathioprine has been used for treatment of autoimmune thrombocytopenia, autoimmune hemolytic anemia, autoimmune skin diseases, chronic hepattitis, myasthenia gravis, immune-mediated glomerulopathy (kidney disorder), chronic atrophic gastritis (inflammation of the stomach) and inflammatory bowel disease.2

Side Effects of Azathioprine

The primary complication encountered with the administration of azathioprine is bone marrow suppression that can result in leukopenia (decreased number of white blood cells), anemia, and thrombocytopenia (a reduction in platelets). Acute pancreatitis and hepatotoxicity may also occur.2


  1. Applied Pharmacology for Veterinary Technicians. Boyce P. Wanamaker, Kathy Lockett Massey
  2. Textbook of small animal surgery. Douglas H. Slatter