Imuran®
GoodRxAzathioprine · oral tablet
Misc.
Approved uses
Prevention of rejection in renal transplantation
Usually 3 to 5 mg/kg daily at the time of transplant, then 1 to 3 mg/kg daily as maintenance
Active rheumatoid arthritis
Initially about 1 mg/kg daily, increased after 6 to 8 weeks and then at 4-week intervals to a maximum of 2.5 mg/kg daily
Test TPMT and NUDT15 before starting: a deficient patient can be catastrophically myelosuppressed at an ordinary dose
OFF-LABELNot in the FDA label for this product
Non-infectious uveitis, scleritis and mucous membrane pemphigoid
Oral, as the sole non-corticosteroid agent; several months before the effect is judged
Cohort · n=145 · slow, 62%
A retrospective cohort of 145 patients starting azathioprine as their only non-corticosteroid agent found 62% gained sustained complete inactivity of inflammation within a year and 47% got prednisone down to 10 mg a day or less while holding control. It suited intermediate uveitis best, where 90% reached sustained inactivity within a year. The two cautions are that it is slow, needing several months to reach its goal, and that roughly a quarter of patients hit a treatment-limiting side effect within the year, though these were typically reversible.
Contraindications
Azathioprine tablets should not be given to patients who have shown hypersensitivity to the drug. Azathioprine tablets should not be used for treating rheumatoid arthritis in pregnant women. Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of malignancy if treated with azathioprine tablets.
Available FormsAzathioprine 50 mg tablets.
Mechanism of ActionAzathioprine is a purine antimetabolite. It is converted to 6-mercaptopurine and then to thioguanine nucleotides, which are incorporated into DNA and suppress the proliferation of rapidly dividing lymphocytes, damping the cell-mediated immune response.
Warnings & Precautions
- Chronic immunosuppression with azathioprine increases the risk of malignancy, including post-transplant lymphoma and hepatosplenic T-cell lymphoma. This carries a boxed warning.
- Severe myelosuppression can occur, particularly in patients with reduced TPMT or NUDT15 activity; test before starting and monitor the blood count.
- Serious infections, including opportunistic infection, may occur.
- Gastrointestinal hypersensitivity presenting as severe nausea and vomiting can occur within the first weeks.
Common Side Effects
The principal and potentially serious toxic effects of azathioprine tablets are hematologic and gastrointestinal. The risks of secondary infection and malignancy are also significant (see WARNINGS ). The frequency and severity of adverse reactions depend on the dose and duration of azathioprine tablets as well as on the patient's underlying disease or concomitant therapies.
Pregnancy & LactationPregnancy: Azathioprine can cause fetal harm; it crosses the placenta and has been associated with intrauterine growth restriction and neonatal myelosuppression.
Lactation: Azathioprine metabolites are present in human milk; a decision should weigh the mother's clinical need against the potential risk.
Pediatric UseSafety and efficacy of azathioprine in pediatric patients have not been established.