Imurel (Azathioprine)

• Azathioprine is used to modulate immune activity in several chronic inflammatory and transplant‑related conditions.
• Organ transplant rejection prevention: reduces the risk of acute and chronic graft rejection by suppressing lymphocyte proliferation.
• Rheumatoid arthritis: alleviates joint inflammation and slows disease progression in patients with moderate to severe disease.
• Inflammatory bowel disease (Crohn's disease, ulcerative colitis): induces and maintains remission by dampening intestinal immune responses.
• Systemic lupus erythematosus: helps control systemic autoimmune activity and prevent organ damage.

• Azathioprine is a purine analog that is converted intracellularly to 6‑mercaptopurine, which interferes with de novo purine synthesis. By inhibiting the formation of DNA and RNA precursors, it blocks the proliferation of rapidly dividing T and B lymphocytes, thereby reducing cellular immune responses and cytokine production. The drug also induces apoptosis of activated immune cells and modulates the expression of adhesion molecules, contributing to its overall immunosuppressive effect.

Azathioprine may cause a range of adverse reactions, varying from mild to potentially life‑threatening.

Common Side Effects

• Nausea and vomiting: gastrointestinal upset occurring early in therapy.
• Loss of appetite: reduced desire to eat.
• Mild leukopenia: slight decrease in white blood cell count.
• Elevated liver enzymes: transient increase in hepatic transaminases.
• Hair thinning: mild alopecia.

Serious or Rare Side Effects

• Severe bone marrow suppression: profound pancytopenia requiring medical intervention.
• Hepatotoxicity: significant liver injury with jaundice or hepatitis.
• Increased infection risk: opportunistic infections due to immunosuppression.
• Pancreatitis: acute inflammation of the pancreas.
• Malignancy: heightened long‑term risk of lymphomas and skin cancers.

• Before initiating azathioprine therapy, several safety considerations should be reviewed.
• Baseline blood tests: obtain complete blood count and liver function tests to assess eligibility.
• Monitor regularly: schedule periodic CBC and liver enzymes to detect toxicity early.
• Infection vigilance: advise patients to report signs of infection promptly.
• Avoid live vaccines: immunosuppression can reduce vaccine efficacy and increase risk.
• Pregnancy and lactation: discuss potential risks with a specialist before use.
• Store at ambient temperature: keep tablets in the original container, protect from moisture and heat.

Azathioprine interacts with several medicines that can alter its efficacy or safety profile.

Major Interactions (Avoid)

• Allopurinol and febuxostat: potentiate azathioprine toxicity, may cause severe bone marrow suppression.
• Warfarin: increased anticoagulant effect, risk of bleeding.
• Live vaccines: may lead to uncontrolled infection.

Moderate Interactions (Monitor Closely)

• Rituximab: additive immunosuppression, monitor infection signs.
• Sulfasalazine: may enhance myelosuppression, check blood counts.
• Antibiotics (e.g., trimethoprim‑sulfamethoxazole): can increase myelosuppressive risk, require monitoring.