アザチオプリン

使用用途

• Inflammatory bowel disease
• Immune-mediated anemia, colitis, immune-mediated skin disease, and acquired myasthenia gravis
• Adjunctive therapy in myasthenia gravis in non-responsive patients
• Lymphoplasmacytic enteritis (if poor response to prednisolone)
• Severe cases of immune-mediated hemolytic anemia (IMHA)
• Acute immune-mediated hemolytic anemia (IMHA) with glucocorticoids
• Severe and refractory inflammatory bowel disease
• Adjunctive treatment of ocular fibrous histiocytomas
• Prevention of rejection of MHCmatched renal allografts (with cyclosporine)
• Perianal fistulas (anal furunculosis)
• Glomerulonephritis
• Chronic hepatitis (to reduce inflammation)

投与方法

考えられる副作用

• Bone marrow suppression (leukopenia, anemia, thrombocytopenia)
• Gastrointestinal distress (vomiting, diarrhea, anorexia)
• Acute pancreatitis
• Hepatotoxicity
• Poor hair growth
• Increased susceptibility to secondary infections
• Increased risk of neoplastic illnesses with long-term use

注意事項と禁忌

• Known hypersensitivity to azathioprine
• Cats (generally contraindicated due to severe, potentially fatal myelotoxicity)
• > **Black Box Warning Equivalent:** Azathioprine is a known **mutagen and teratogen**. Pregnant women or those trying to conceive should avoid handling this medication. If handling is necessary, strict use of protective gloves is required. * **Hepatic Dysfunction:** Use with extreme caution in patients with pre-existing liver disease, as hepatotoxicity is a known adverse effect. * **Thiopurine Methyltransferase (TPMT) Deficiency:** Dogs have variable TPMT activity (similar to humans). Dogs with low TPMT activity are at a significantly higher risk for severe bone marrow suppression. * **Tapering:** In recovering patients (e.g., IMHA), withdrawal of the drug must be tapered very slowly over several months. Rapid withdrawal can trigger a rebound hyperimmune response and fatal relapse. * **Pregnancy/Nursing:** FDA Category D (human). Distributed into milk; use milk replacer if the dam is treated.

薬物相互作用

• ACE Inhibitors (e.g., benazepril, enalapril): Increased potential for hematologic toxicity
• Allopurinol: Decreases hepatic metabolism of azathioprine; significantly increases toxicity risk. Dose of azathioprine must be reduced to 1/4 to 1/3 of the usual dose if used concurrently.
• Aminosalicylates (e.g., sulfasalazine, mesalamine, olsalazine): Increased risk for azathioprine toxicity
• Non-depolarizing muscle relaxants (e.g., pancuronium, tubocurarine): Neuromuscular blocking activity may be inhibited or reversed by azathioprine
• Corticosteroids: Often used together intentionally, but carries a greater potential risk for overall toxicity development
• Drugs affecting myelopoiesis (e.g., trimethoprim/sulfa, cyclophosphamide): Increased potential for hematologic toxicity (additive bone marrow suppression)
• Warfarin: Potential for reduced anticoagulant effect
• Aminosalicylates: Increased risk of azathioprine toxicity.
• ACE inhibitors: May increase the potential for haematological adverse events (e.g., severe anaemia or leucopenia).

よくある質問