Oprisine (Azathioprine)

Azathioprine is used across several immune‑mediated pathways to control abnormal immune activity.

• Prevention of organ transplant rejection: helps maintain graft function by suppressing immune response.
• Autoimmune hepatitis: reduces liver inflammation and improves biochemical markers.
• Rheumatoid arthritis: alleviates joint inflammation and slows disease progression.
• Inflammatory bowel disease (Crohn’s disease and ulcerative colitis): diminishes intestinal inflammation and maintains remission.
• Systemic lupus erythematosus: moderates systemic immune activation and organ involvement.

• Azathioprine is a pro‑drug that is converted intracellularly to 6‑mercaptopurine, which interferes with purine synthesis. This inhibition reduces lymphocyte proliferation and impairs DNA/RNA synthesis, leading to broad suppression of cell‑mediated and humoral immune responses.

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

Common Side Effects

• Nausea and vomiting: occasional gastrointestinal upset.
• Elevated liver enzymes: mild, transient increases in hepatic enzymes.
• Leukopenia: reduced white‑blood‑cell count, often mild.
• Rash or mild skin irritation: occasional dermatologic reaction.
• Fatigue: general feeling of tiredness.
• Mild headache: occasional cephalic discomfort.

Serious or Rare Side Effects

• Severe bone‑marrow suppression: profound pancytopenia requiring medical intervention.
• Hepatotoxicity: significant liver injury with jaundice or elevated transaminases.
• Opportunistic infections: increased susceptibility to bacterial, viral or fungal infections.
• Malignancies: heightened risk of lymphomas and skin cancers with long‑term use.
• Pancreatitis: inflammation of the pancreas presenting with abdominal pain.
• Severe hypersensitivity reactions: including Stevens‑Johnson syndrome or drug‑induced fever.

Azathioprine requires careful monitoring and patient education before and during therapy.

• Baseline testing: obtain complete blood count and liver function tests prior to initiation.
• Regular monitoring: schedule periodic CBC and liver panels to detect toxicity early.
• Infection risk: advise patients to report fever, cough or unexplained infections promptly.
• Pregnancy and lactation: discuss potential risks and consider alternative therapies when possible.
• Drug interactions: review concomitant medications for possible synergistic myelosuppression.
• Store at ambient temperature: keep tablets in original container, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Allopurinol and febuxostat: increase risk of bone‑marrow suppression.
• Ribavirin: additive myelosuppressive effect.
• Live vaccines: heightened risk of infection due to immunosuppression.

Moderate Interactions (Monitor Closely)

• Warfarin: may enhance anticoagulant effect, requiring INR monitoring.
• ACE inhibitors: potential for increased nephrotoxicity.
• Anticonvulsants (e.g., phenytoin): may affect azathioprine metabolism.
• NSAIDs: can worsen renal function when combined with azathioprine.