Azathioprine

Azathioprine is an immunosuppressant, which means it is a drug whose purpose is to weaken the immune system. It is the generic name for a drug that goes under the brand names Imuran, Azasan, and Azamun, and is available in tablet form, as an injection, or intravenously. Azathioprine is given to patients who are anticipating an organ transplant or who have already been given a new organ, in order to help prevent rejection by the immune system. It is also given to reduce the signs and symptoms of rheumatoid arthritis, which is a disorder in which the immune system attacks the joints and causes severe pain. In some cases, azathioprine is used to treat ulcerative colitis, which is a chronic condition which causes pain and diarrhea in the intestines. Other inflammatory conditions that can be treated by azathioprine are systemic lupus erythematosus, inflammatory myositisis, inflammatory bowel disease, and vasculitis. It generally takes six to eight weeks for your condition to improve, though it sometimes takes up to twelve.

Azathioprine can have several different side effects. Most importantly, it can cause a decrease in the number of blood cells in your bone marrow. You should call your doctor if you have any unusual bleeding or bruising, fatigue, headache, confusion or dizziness, increased heart rate, weakness, difficulty breathing, sore throat, fever, chills, or any signs of infection. It could also increase your risk of developing some cancers, such as skin cancer and lymphoma. You should let your doctor know if you have ever taken any cancer medications, or if you find suspicious lumps or masses on your body.

In addition to the rare but serious side effects above, azathioprine can cause an upset stomach, vomiting or diarrhea, muscle soreness, blurred vision, mouth sores, coughing, lack of energy or appetite, flu-like symptoms, rash, or yellowing of the skin or eyes. You should contact your doctor if these effects are severe or do not go away. During the course of your treatment with azathioprine, you should be receiving regular blood tests in order to ensure that these effects are not inhibiting your treatment. Some people are not able to take azathioprine, or may require a lower dose or special monitoring if they do take it.

Studies about the effects of azathioprine offer contradicting conclusions about the safety of this medication for pregnant women. Early studies seemed to indicate that azathioprine would not cause any deformities or problems for a developing fetus, and that there was very little risk for pregnant women or their babies. Recent studies, however, seem to suggest that fetal harm can result from taking azathioprine, though no conclusions have been reached as to how much harm or what doses put a fetus in danger. Because of the uncertainty surrounding this subject, you should exercise extreme caution if you are pregnant and considering treatment with azathioprine. You also should not breast feed while taking this medication, since it is considered a cytotoxic drug and can be harmful to babies.

Azathioprine has the following structural formula:

Review published on: 20 January 2008