Imuran (Azathioprine)

Imuran (azathioprine) is a cytotoxic (cell-killing) compound approved by the U.S. Food and Drug Administration (FDA) and used to treat sarcoidosis in patients who are resistant to or cannot tolerate steroid treatments.

Generic formulations of this treatment are available, and it is an alternative to methotrexate, which some patients cannot take because of liver or kidney damage.

How Imuran works

Sarcoidosis is a chronic inflammatory disease, which can affect different tissues or organs by causing the formation of clumps of inflammatory cells called granulomas in them. These granulomas can interfere with the normal function of tissues and organs, eventually leading to tissue scarring and, in severe cases, to organ failure.

Imuran is a so-called antimetabolite, a compound that is very similar to natural ones but that interferes with the normal function of cells. It works by slowing the synthesis of DNA. When cells duplicate, they make a complete copy of their genome before dividing into two new cells. Imuran resembles one of the building blocks that cells use to make DNA, but it does not work as normal DNA.

Because some cells — like bone marrow cells that produce immune cells, cancer cells, and skin cells — are fast-growing, DNA synthesis occurs at a higher rate and they are particularly sensitive to Imuran.

Imuran in clinical trials

study published in the American Journal of Ophthalmology analyzed the effect of azathioprine in patients with non-infectious eye inflammation, which can sometimes be caused by sarcoidosis; 24 percent of these people did not respond to other immunosuppressant treatments. Azathioprine significantly eased the eye inflammation, allowing lower systemic corticosteroid doses to be used. After 18 months of treatment, 24 to 35 percent of patients showed no signs of eye inflammation.

An observational clinical trial (NCT02356445) is ongoing in up to 2,000 sarcoidosis patients in Ohio to investigate outcomes in people using azathioprine, methotrexate, and several other treatments that suppress the immune system. The study will compare the different treatments by documenting the number and type of adverse reactions in patients over time, and collect data on improvements in patient outcomes.

Additional information

Because Imuran weakens the immune system, patients using this medication are more prone to infections. The most common side effects include nausea, hair loss, and rashes.


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