Azathioprine (Imuran) for Pulmonary Fibrosis

Azathioprine (brand name Imuran) is an immunosuppressant, or drug that suppresses the immune system. It is used together with other medications to prevent rejection of transplants. It is also used to treat inflammatory diseases, connective tissue diseases, and autoimmune diseases when other medications and treatments do not work.

Although it is also used to treat pulmonary fibrosis, newly diagnosed patients should not start treatment with Imuran due to the interim results of a clinical trial called PANTHER-IPF (NCT00650091), which showed that a triple-drug therapy of prednisone, azathioprine, and N-acetylcysteine may be potentially harmful for people with pulmonary fibrosis.

About the PANTHER-IPF trial

The study was designed to assess the safety and benefits of treatments used for pulmonary fibrosis. It compared the triple-drug therapy with placebo to N-acetylcysteine with placebo, on lung function and other outcomes in newly diagnosed patients.

The triple-drug therapy arm of the study was stopped because participants treated with the combination therapy had higher mortality rates, more serious adverse events, and more discontinuations. The deaths were due to a variety of causes, with about half appearing to be due to respiratory disease.


The usual dose of Imuran is 50 mg once daily for two weeks, then increased by 25 mg increments every seven to 14 days until a maintenance dose of 2-3 mg per kg per day (with a maximum of 150 mg per day). When there is evidence of a therapeutic response, the dose can be maintained, although it should be reduced to the lowest level that leads to a therapeutic response.

Side effects

Common side effects of Imuran include fever and chills, nausea, vomiting, liver function abnormalities, bone marrow toxicity, skin rash or hives, and stomach discomfort.

Patients taking the triple-drug combination should discuss with their doctor the benefits of maintaining this therapy. Patients taking prednisone, azathioprine, or combinations of the two should also discuss with their doctor whether the results of the PANTHER-IPF study apply to their condition, along with treatment options. Prednisone should not be stopped abruptly.

Note: Pulmonary Fibrosis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. 

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