Imuran (azathioprine) is an immunosuppressive medication widely utilized in the management of autoimmune diseases and prevention of organ transplant rejection. As an antimetabolite and purine analogue, it modulates the immune system by inhibiting purine synthesis, thereby reducing the proliferation of lymphocytes. This mechanism makes it a cornerstone therapy in conditions where uncontrolled immune activity leads to tissue damage. Its established efficacy and extensive clinical history position it as a reliable option for long-term immunomodulation under specialist supervision.

Features

• Active ingredient: Azathioprine
• Available formulations: Oral tablets (25 mg, 50 mg, 75 mg, 100 mg)
• Pharmacologic class: Immunosuppressive agent; purine analogue
• Half-life: Approximately 5 hours for azathioprine; active metabolites have longer half-lives
• Metabolism: Hepatic, via xanthine oxidase and thiopurine methyltransferase (TPMT)
• Excretion: Primarily renal

Benefits

• Effectively reduces immune-mediated inflammation in autoimmune disorders such as rheumatoid arthritis and lupus
• Decreases risk of acute and chronic organ transplant rejection when used as part of immunosuppressive regimens
• Allows for reduction in corticosteroid dosing, mitigating long-term steroid-related adverse effects
• Supports remission maintenance in inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis)
• Provides flexible dosing adaptable to individual patient tolerance and therapeutic response
• Well-established safety and efficacy profile with decades of clinical use and research

Common use

Imuran is indicated for the prophylaxis of rejection in renal transplantation, often in combination with other immunosuppressive agents. It is also approved for the management of severe, active rheumatoid arthritis unresponsive to conventional treatments. Off-label uses include treatment of autoimmune hepatitis, systemic lupus erythematosus, inflammatory bowel disease, myasthenia gravis, and certain dermatological conditions such as pemphigus vulgaris. Its role typically involves long-term maintenance therapy rather than acute symptom management.

Dosage and direction

Dosage must be individualized based on indication, patient weight, renal function, and TPMT enzyme activity. For transplant rejection prophylaxis: initial dose is usually 3–5 mg/kg/day, then maintenance at 1–3 mg/kg/day. In rheumatoid arthritis: start with 1 mg/kg/day (50–100 mg), increasing by 0.5 mg/kg after 6–8 weeks if needed, to a maximum of 2.5 mg/kg/day. Administer orally in divided doses or as a single daily dose, with or after food to minimize gastrointestinal upset. Regular monitoring of complete blood count and liver function is mandatory.

Precautions

Patients should be informed of the increased risk of infections and malignancies associated with immunosuppression. Regular blood tests are essential to monitor for myelosuppression (leukopenia, thrombocytopenia) and hepatotoxicity. Live vaccines are contraindicated during treatment. Use with caution in patients with renal impairment, hepatic disease, or known TPMT deficiency. Pregnancy and breastfeeding require careful risk-benefit assessment—azathioprine is FDA Pregnancy Category D. Patients should report signs of infection, unusual bleeding, or jaundice promptly.

Contraindications

Imuran is contraindicated in patients with known hypersensitivity to azathioprine or any component of the formulation. It should not be used in patients who have previously exhibited severe bone marrow suppression on this or similar agents. Concomitant use with live vaccines is contraindicated. Patients with absent TPMT activity should generally not receive azathioprine due to high risk of severe myelotoxicity.

Possible side effect

Common side effects include nausea, vomiting, diarrhea, and mild leukopenia. Serious adverse reactions may include severe bone marrow suppression (pancytopenia), hepatotoxicity (elevated transaminases, cholestasis), increased susceptibility to opportunistic infections, and gastrointestinal ulceration. Long-term use is associated with elevated risk of lymphoma, skin cancers, and other malignancies. Less frequently, pancreatitis, alopecia, and fever may occur.

Drug interaction

Significant interactions include allopurinol, which inhibits xanthine oxidase and markedly increases azathioprine toxicity—dose reduction of azathioprine by ⅔–¾ is required. Warfarin effect may be reduced. Concurrent use with other myelosuppressive agents (e.g., sulfasalazine, ACE inhibitors) may exacerbate bone marrow suppression. Live vaccines should be avoided.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next dose. Doubling the dose to compensate for a missed dose is not recommended. Patients should maintain regular dosing schedules to ensure consistent immunosuppression.

Overdose

Overdose may present as severe nausea, vomiting, diarrhea, and signs of myelosuppression (infections, bleeding). Leucovorin may be administered as a rescue therapy. Management is supportive, including hematological monitoring, infection prophylaxis, and possibly transfusions. Hemodialysis is not effective due to high protein binding.

Storage

Store at room temperature (15–30°C) in a dry place, protected from light. Keep in the original container, tightly closed. Do not use beyond the expiration date. Keep out of reach of children and pets.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice. Diagnosis and treatment should be performed by a qualified healthcare provider. Individual response to therapy may vary. Always follow the prescribing information provided with the medication.

Reviews

Clinical studies and long-term observational data support the efficacy of Imuran in reducing disease activity in autoimmune conditions and preventing transplant rejection. Many patients experience significant improvement in symptoms and quality of life. However, reviews often note the necessity for vigilant monitoring due to potential adverse effects. Patient experiences vary, with some reporting good tolerance and others encountering side effects requiring discontinuation or dose adjustment.