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Azathioprine and 6-mercaptopurine

Generic Names: Azathioprine and 6-mercaptopurine (or 6-MP)
Brand Names: Azasan®, Imuran® (azathioprine) and Purinethol® (6-mercaptopurine)
Drug Class: Immunosuppressant /Immunomodulator

What does this medication do?

6-MP (6-mercaptopurine or Purinethol®) and azathioprine (Azasan,Imuran®) are medications used to help keep patients with Crohn's disease or ulcerative colitis feeling well, and off steroids. They appear to work by decreasing the activity of the immune system. This results in decreased inflammation in the intestine and may also help to close fistulas in patients with Crohn's disease. These medications are slow acting, and can take up to 3 months to work.

How effective are 6-mercaptopurine and azathioprine for Crohn's disease and ulcerative colitis?

These medications are some of the most effective maintenance treatments we have for Crohn's disease and ulcerative colitis. Studies suggest that approximately 66% (2 out of 3) of patients respond to these treatments.

These are safe medications; however, there are rare side effects which include:

  1. Allergy. Some patients may develop a fever, rash, and/or joint aches, which usually occurs within the first month after starting treatment and resolves with time after the medication is discontinued. Please call should you develop any of these symptoms.
  2. Pancreatitis (inflammation of the pancreas). Pancreatitis occurs in approximately 2% (2 out of 100) patients. It usually occurs within the first month of treatment. Symptoms include nausea, vomiting, or upper abdominal pain. It typically reverses once the medication is stopped. Should you develop abdominal pain and/or vomiting, please hold the medication and contact us immediately.
  3. Nausea and/or vomiting. The most common of these side effects is mild nausea. Many people find that taking the medication in the evening allows you to sleep through the nausea. Please let us know if you become nauseous or vomit.
  4. Abnormal liver function tests. An increase/elevation in liver tests is seen in about 10% (1 out of 10) of patients, and usually responds to reducing the dose of medication.
  5. Low blood counts. Neutropenia is a decrease in the number of the body's white blood cells (WBC's) which help fight off infection. A low WBC can be seen in 2-5% (2-5/100) of patients, and typically reverses when the medication is adjusted. The medication may also cause Thrombocytopenia, a decrease the number of platelets (PLT) in the blood which are necessary for proper clotting. It may also cause anemia (low red blood cell counts). We may adjust the dose of medication depending on the blood counts.
  6. Infection. You will be at a slightly higher risk than the general population for developing infections. Please call us and your primary care physician with any signs and symptoms of infection including fevers, chills, night sweats, cough, etc. There is no reason to avoid your normal daily activities.
  7. Lymphoma. There is a rare reported, risk of lymphoma (tumor of the lymph glands) in patients receiving immunodulator therapy with what is likely a 4 x increase risk over the general population. This translates to a risk of lymphoma in 4 out of 10,000 patients receiving immunodulator therapy. There have been 19 cases of a rare but fatal lymphoma (hepatosplenic t-cell lymphoma) in patients taking both infliximab (Remicade) and 6MP/Azathioprine. There are also 4 reports of this rare lymphoma occurring in patients taking both Humira (adalimumab) and 6MP/Azathioprine.

In order for us to help monitor your response to this medication, you will initially be required to have weekly blood tests, and then at prescribed intervals thereafter. Should you choose to have your blood drawn at a local laboratory, we will provide you with a standing order. If this is the case, we ask that you ensure that the results are faxed to us as soon as available, and that you call us a few days after they are drawn to review the results. You will receive a copy of all labs and will be notified if changes are necessary. If you do not hear from us either by telephone or in writing within 2 weeks after your blood is drawn, please call the office at (617)-667-2802.

How to take the medication and miscellaneous facts:

  • You should take this medication at the same time everyday.
  • If you miss a dose, take it as soon as you remember.
  • Do not take this medication with milk, as it may decrease the absorption of the medication.
  • You may take this medication with food.
  • You should not receive live vaccines (ex. MMR-Measles, Mumps, & Rubella, chicken pox, nasal flu, varicella) while taking this medication.
  • Inactivated vaccines (ex. Tetanus, influenza, pneumonia, and Gardisil for prevention of HPV, the Human Pappiloma Virus) are safe and recommended. It is a good idea to call your doctor or nurse before receiving any vaccinations.
  • Please be sure that you have your annual health maintenance including PAP smears, mammogram, etc.
  • Please check with us prior to starting any new medications, herbs, or vitamins, since many medications may interfere with its absorption.
  • DO NOT START ALLOPURINOL before checking with us. This medication interacts with 6MP and a dose adjustment will be necessary.