硫唑嘌呤
Azathioprine
Azathioprine / Azathioprine Sodium
別名: Imuran · Azasan · Azathioprinum · BW-57322 · NSC-39084
由 VetSheet 獸醫團隊審訂更新於 2026年4月5日本內容以實證獸醫文獻為本
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Inflammatory bowel disease | Initially 2 mg/kg PO once daily for 2 weeks, then tapered to 2 mg/kg PO every other day for 2-4 weeks, then 1 mg/kg PO every other day. | PO | q24h then tapered | Long-term | 🌎 NA |
| Immune-mediated anemia, colitis, immune-mediated skin disease, and acquired myasthenia gravis | 2 mg/kg PO once daily (q24h); long-term therapy 0.5-1 mg/kg PO every other day | PO | q24h then q48h | Long-term | 🌎 NA |
| Adjunctive therapy in myasthenia gravis in non-responsive patients | Initially, 1 mg/kg PO once daily. If neutrophil and platelet counts are normal after 2 weeks, dose is increased to 2 mg/kg PO once daily. | PO | q24h | Until clinical remission | 🌎 NA |
| Lymphoplasmacytic enteritis (if poor response to prednisolone) | 2 mg/kg PO once daily for 5 days, then on alternate days to prednisolone | PO | q24h then q48h | Long-term | 🌎 NA |
| Severe cases of immune-mediated hemolytic anemia (IMHA) | 2.2 mg/kg PO once daily (q24h) | PO | q24h | Long-term | 🌎 NA |
| Acute immune-mediated hemolytic anemia (IMHA) with glucocorticoids | 1-2 mg/kg PO once daily | PO | q24h | Long-term maintenance | 🌎 NA |
| Severe and refractory inflammatory bowel disease | 2.2 mg/kg PO once daily | PO | q24h | Long-term | 🌎 NA |
| Adjunctive treatment of ocular fibrous histiocytomas | 2 mg/kg PO daily for 2 weeks, reevaluate, and reduce to 1 mg/kg every other day for 2 weeks, then 1 mg/kg once weekly for 1 month | PO | Tapering schedule | 10 weeks | 🌎 NA |
| Prevention of rejection of MHCmatched renal allografts (with cyclosporine) | 1-5 mg/kg PO every other day | PO | q48h | Long-term | 🌎 NA |
| Perianal fistulas (anal furunculosis) | Initially 2 mg/kg PO once daily (q24h)... Then reduce to 2 mg/kg PO every other day (q48h) and continued for 12 weeks... After 12 weeks, reduce dose to 1 mg/kg PO every other day (q48h) | PO | Tapering schedule | 12 months | 🌎 NA |
| Glomerulonephritis | 2 mg/kg PO once daily | PO | q24h | Unspecified | 🌎 NA |
| Chronic hepatitis (to reduce inflammation) | 2.2 mg/kg PO once daily in combination with corticosteroids... Azathioprine dose is given every other day after 1-2 weeks. | PO | q24h then q48h | Long-term | 🌎 NA |
| Immune-mediated diseases (e.g., IMHA, polyarthritis) | 2 mg/kg p.o. q24h for a maximum of 2-3 weeks, then 0.5-2 mg/kg p.o. q48h | PO | q24h initially, then q48h | Max 2-3 weeks for initial q24h dosing, then maintenance | 🌍 EU |
- Inflammatory bowel disease: May take 2-6 weeks before beneficial effects are seen.
- Immune-mediated anemia, colitis, immune-mediated skin disease, and acquired myasthenia gravis: With prednisolone administered on the alternate days.
- Adjunctive therapy in myasthenia gravis in non-responsive patients: Taper to every other day when clinical remission occurs. Discontinue if WBC <4,000 cells/mcL or neutrophils <1,000 cells/mcL.
- Severe cases of immune-mediated hemolytic anemia (IMHA): In addition to prednisone. Tapered gradually.
- Acute immune-mediated hemolytic anemia (IMHA) with glucocorticoids: Used for long-term maintenance as steroid side effects become intolerable.
- Severe and refractory inflammatory bowel disease: A lag time of 3-5 weeks is expected before clinical improvement is noted.
- Perianal fistulas (anal furunculosis): Dose reduced based on clinical response or myelosuppression markers.
- Glomerulonephritis: Immunosuppressive treatment is controversial.
- Immune-mediated diseases (e.g., IMHA, polyarthritis): Often used in conjunction with corticosteroids. Clinical response may take up to 6 weeks.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Severe and refractory inflammatory bowel disease | 0.3 mg/kg PO once every other day | PO | q48h | Long-term | 🌎 NA |
| Immune-mediated diseases | Not recommended | PO | Not recommended | Not recommended | 🌍 EU |
- Severe and refractory inflammatory bowel disease: Must be used with extreme caution due to myelotoxicity. May take 3-5 weeks for beneficial effects.
- Immune-mediated diseases: Cats often develop severe, non-responsive fatal leucopenia and thrombocytopenia.
雪貂
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Inflammatory bowel disease | 0.9 mg/kg PO q24-72h | PO | q24-72h | Unspecified | 🌎 NA |
- Inflammatory bowel disease: Used alongside prednisone and dietary management.
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Immunosuppressive | 3 mg/kg PO q24h | PO | q24h | Unspecified | 🌎 NA |
| Autoimmune skin diseases (e.g., pemphigus foliaceous) | 13 mg/kg PO q24h for 1 month, then every other day (q48h) | PO | q24h then q48h | Long-term | 🌎 NA |
- Immunosuppressive: Appears to be a relatively safe immunosuppressive treatment in the horse.
- Autoimmune skin diseases (e.g., pemphigus foliaceous): Used as a steroid-sparing drug. May cause thrombocytopenia.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
概覽
硫唑嘌呤 (Azathioprine) 是一種強效的嘌呤拮抗型免疫抑制劑，在獸醫學中廣泛用於犬隻，以治療多種免疫介導和自體免疫性疾病（例如：免疫介導性溶血性貧血 [IMHA]、炎症性腸病 [IBD]、重症肌無力及天皰瘡）。
臨床關鍵要點：
- 減少類固醇用量 (Steroid-Sparing Effect)： 通常與皮質類固醇（如潑尼松或潑尼松龍）合併使用。這種組合允許逐漸減少類固醇的劑量，從而在維持疾病緩解的同時，將長期的類固醇副作用降至最低。
- 起效緩慢： 硫唑嘌呤並非速效藥物。通常需要 2至6週 才能達到完全的免疫抑制臨床療效。因此，它不適合單獨用於急性、危及生命的自體免疫危機。
- 物種敏感性： 貓對硫唑嘌呤極度敏感，容易引發骨髓抑制，這是因為貓體內的硫嘌呤甲基轉移酶 (TPMT) 濃度天生較低。在貓科動物中使用此藥極具爭議，通常應避免使用。
- 毒性風險： 最顯著的副作用是 骨髓抑制（白血球低下、貧血、血小板低下）。在犬隻中，肝毒性和急性胰臟炎也是值得注意的風險。
作用機轉
Azathioprine is a prodrug that must be metabolized to exert its effects.
- Pathway: Azathioprine is rapidly converted in the body (primarily in erythrocytes and the liver) to 6-mercaptopurine (6-MP).
- 6-MP is further metabolized into active thioguanine nucleotides (TGNs).
- Mechanism: These active metabolites act as purine antagonists. They are falsely incorporated into cellular DNA and RNA, which inhibits purine metabolism, RNA/DNA synthesis, and cellular mitosis.
- Immunological Effect: Because lymphocytes (T-cells and B-cells) lack a salvage pathway for purine synthesis and rely heavily on de novo synthesis, they are profoundly affected. This leads to a marked suppression of delayed hypersensitivity and cellular immunity, with a lesser effect on humoral antibody responses.
安全性與警告
禁忌症
- Known hypersensitivity to azathioprine
- Cats (generally contraindicated due to severe, potentially fatal myelotoxicity)
不良反應
- 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
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.
藥物交互作用
Increased potential for hematologic toxicity
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.
Increased risk for azathioprine toxicity
Neuromuscular blocking activity may be inhibited or reversed by azathioprine
Often used together intentionally, but carries a greater potential risk for overall toxicity development
Increased potential for hematologic toxicity (additive bone marrow suppression)
Potential for reduced anticoagulant effect
Increased risk of azathioprine toxicity.
May increase the potential for haematological adverse events (e.g., severe anaemia or leucopenia).
監測
- Hemograms (CBC including platelets): Monitor closely; initially every 1-2 weeks, then every 1-2 months on maintenance therapy. Reduce dose by 25% if WBC drops to 5,000-7,000 cells/mcL. Discontinue if WBC < 5,000 cells/mcL until resolved.
- Liver function tests (ALT, AST, ALP, Bilirubin)
- Serum amylase/lipase (if pancreatitis is suspected)
- Clinical efficacy and signs of secondary infection
藥物動力學
吸收
Poorly absorbed from the gastrointestinal tract.
分佈
Rapidly taken up by lymphocytes and erythrocytes. Distributed into milk.
代謝
Rapidly metabolized to mercaptopurine (6-MP). Mercaptopurine is further metabolized to several other compounds via pathways including thiopurine methyltransferase (TPMT). Cats have naturally low TPMT activity, making them highly susceptible to toxicity.
排除
Metabolites are excreted primarily by the kidneys. Only minimal amounts of azathioprine or mercaptopurine are excreted unchanged.
過量
There is limited specific information regarding acute overdose of azathioprine in veterinary patients.
- Decontamination: If ingestion was recent, use standard protocols to empty the GI tract (emesis induction, activated charcoal).
- Treatment: Provide aggressive supportive care. Monitor hematologic parameters closely for delayed bone marrow suppression.
- Consultation: Contact an animal poison control center for the most up-to-date guidance.
可用產品
劑型
- Tablets
- Injection (powder for reconstitution)
- Compounded oral suspension
人用標示
- Azathioprine Tablets: 50 mg, 75 mg & 100 mg (Azasan®, Imuran®, generic)
- Azathioprine Sodium Injection: 100 mg (as sodium)/vial in 20 mL vials (generic)
各地核准狀態
POM (Prescription Only Medicine). Handled under cascade using human formulations.
POM-V / POM. Handled under the prescribing cascade.
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Tablets should be stored at room temperature in well-closed containers and protected from light. Sodium powder for injection should be stored at room temperature and protected from light; after reconstitution, it must be used within 24 hours as it contains no preservatives. Compounded oral suspensions have optimal stability between pH 5.5 and 6.5 and should be protected from light.
飼主須知
寵物主人重要須知：
- 需要耐心等待： 此藥物需要時間才能發揮作用。可能需要 數週 才能看到寵物病情改善。未經獸醫師同意，請勿自行停藥。
- 安全與操作： 硫唑嘌呤是一種強效藥物，可能影響人類DNA。處理藥片後請 徹底洗手。如果您懷孕、準備懷孕或正在哺乳，請 避免接觸此藥物，若必須處理，請務必戴上防護手套。
- 注意副作用： 由於此藥會抑制免疫系統並可能影響骨髓，您的寵物感染和出血的風險會增加。
- 何時應聯繫獸醫師： 如果您的寵物出現 異常出血、不明原因的瘀青、牙齦蒼白、發燒、食慾不振、嘔吐、腹瀉或精神沉鬱 等症狀，請立即聯繫您的獸醫師。
- 嚴格監控： 您的寵物將需要頻繁的血液檢查（尤其是在最初幾個月），以確保藥物沒有損害其骨髓或肝臟。請務必按時回診。
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