Azathioprine

What is Azathioprine?

• Azathioprine, its tradename Imuran, is in a class of medications called Disease Modifying Anti-Rheumatic Drugs, or DMARDs.
• DMARDs are a slow acting but effective treatment for rheumatoid arthritis and other forms of inflammatory arthritis.
• Azathioprine most often is used in the treatment of lupus and other connective tissue diseases such as vasculitis, myositis and others.

What is the typical dose for Azathioprine?

• Azathioprine comes in tablet form. It is prescribed daily in most cases. The dose varies based on the patient’s weight. Most rheumatologists will start Azathioprine at a lower dose and slowly increase to the goal dose.

How does Azathioprine work?

• While there has been extensive research into this area, it remains unclear as to the exact mechanism of action. Its primary mechanism is through an effect it has on lymphocyte function, a specific type of white blood cell.

How soon will I feel the effects of azathioprine?

• Like all DMARDs, azathioprine takes time to work. Most patients start to feel the positive effects of azathioprine at 4-8 weeks, with maximum benefit at 3-6 months. Side effects can occur earlier.

What are the possible side effects of azathioprine?

• Stomach upset, including nausea and vomiting
• Skin Rash
• Lower blood counts
• Liver irritation
• Increased risk for lymphoma

How can I lower the risk of side effects?

• Follow the directions your physician has provided.
• A very small percentage of people lack the enzyme which processes the active metabolite of azathoprine in the body, placing increased risk for developing serious side effects.
• By starting at a low dose and completing regular blood work, your doctor can safely monitor you to reduce this risk.
• Do your regularly scheduled bloodwork as requested by your doctor.

Are there any medications to avoid when taking azathioprine?

• Allopurinol blocks the body’s metabolism of azathioprine. It is possible to take both safely, but your doctor must closely monitor your medication doses.
• Sulfa based medications must also be used with caution.

What should I do if I miss a dose?

• You can safely take your dose later in the day. If you do not remember until the next day, just take your regular dose; do not take a double dose. As long as this does not happen regularly, you should not experience any ill effects.

How can I safely stop azathioprine?

• It is safe to just stop azathioprine; you do not need to slowly reduce the dose. However, keep in mind, if you were gaining any benefit from azathioprine, it will usually take at least 6 weeks to lose it.

For more information about azathioprine, or for questions that are specific to your situation, always consult your physician.