← Search & browse all drugs
ANTINEOPLASTIC AND IMMUNOMODULATING AGENTS › IMMUNOSUPPRESSANTS › IMMUNOSUPPRESSANTS › Other immunosuppressants
azathioprine
L04AX01
Forms & Strengths
- Oral tablets: 50 mg
- Intravenous powder for injection: 100 mg per vial
Adult Dosing
- Renal transplantation: 3 to 5 mg/kg daily initially, maintained at 1 to 3 mg/kg daily
- Rheumatoid arthritis: 1 mg/kg (approx. 50-100 mg) daily in 1-2 divided doses, increased by 0.5 mg/kg/day after 6-8 weeks if needed up to max 2.5 mg/kg/day
- Crohn's disease / Ulcerative colitis: 1.5 to 2.5 mg/kg daily
Pediatric Dosing
- Renal transplantation (children > 1 month): Same as adult dosing on a mg/kg basis (1 to 3 mg/kg daily)
- Inflammatory bowel disease (off-label): 1 to 2.5 mg/kg daily
Indications
- Prophylaxis of organ rejection in renal homotransplantation
- Active rheumatoid arthritis
- Management of moderate to severe active Crohn's disease
Mechanism of Action
- Purine antimetabolite acting as a prodrug for 6-mercaptopurine (6-MP)
- Competes with hypoxanthine and guanine for hypoxanthine-guanine phosphoribosyltransferase (HGPRT), incorporating into DNA/RNA to inhibit purine synthesis
- Suppresses cell-mediated immunity and suppresses antibody production
Contraindications
- Hypersensitivity to azathioprine or mercaptopurine
- Treatment of rheumatoid arthritis in pregnant women
- Prior severe toxicity (e.g., pancreatitis, severe bone marrow suppression) related to mercaptopurine or azathioprine
Adverse Reactions
- Bone marrow suppression (leukopenia, thrombocytopenia, anemia)
- Increased risk of infection and malignancy (lymphoma, skin cancers)
- Gastrointestinal disturbances (nausea, vomiting, diarrhea)
- Hepatotoxicity (elevated liver enzymes, cholestatic jaundice)
- Pancreatitis
Drug Interactions
- Allopurinol or febuxostat: inhibits xanthine oxidase, increasing levels and toxicity of azathioprine/6-MP; reduce azathioprine dose by 75%
- Aminosalicylate derivatives (mesalamine, olsalazine, sulfasalazine): inhibit thiopurine S-methyltransferase (TPMT), increasing myelosuppression risk
- Warfarin: azathioprine may inhibit the anticoagulant effect of warfarin
- ACE inhibitors: may induce severe leukopenia when co-administered with azathioprine
- Live vaccines: risk of severe or fatal infection due to immunosuppression
Curated Content: Needs Vetting Before Put to Clinical Use