巰嘌呤
Mercaptopurine
6-mercaptopurine
別名: Purinethol · Flocofil · Ismipur · Mercaptina · Puri-Nethol · Varimer · 6-mercaptopurine · 6-MP · 6MP · mercaptopurinum · NSC-755 · purinethiol · WR-2785
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
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| As an immunosuppressant in combination with corticosteroids for treating bullous pemphigoid | 2.2 mg/kg | PO | once daily (q24h), then q48h | — | 🌎 NA |
| For erosive, immune-mediated polyarthritis in combination with corticosteroids | 2 mg/kg | PO | once daily (q24h) for 14-21 days, then q48h (every other day) | 14-21 days initially | 🌎 NA |
| For treatment of immune-mediated diseases or acute lymphocytic and granulocytic leukemias | 50 mg/m2 | PO | once daily (q24h) to effect, then every other day (q48h) or as needed | — | 🌎 NA |
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
概覽
巰嘌呤 (Mercaptopurine, 6-MP) 是一種硫嘌呤類抗腫瘤藥物與免疫抑制劑。
臨床要點與藥理學：
- 它與硫唑嘌呤 (Azathioprine) 密切相關，硫唑嘌呤實際上是一種前驅藥，在體內會迅速轉化為巰嘌呤。
- 雖然在獸醫學中較少作為第一線藥物使用，但它可作為淋巴肉瘤、急性白血病以及嚴重的免疫介導疾病（如類風濕性關節炎或難治性自身免疫疾病，例如對治療無反應的潰瘍性結腸炎/炎症性腸病）的有效輔助療法。
- 由於它是一種細胞毒性藥物，需要小心處理，並嚴格監測病患是否出現骨髓抑制和肝毒性。
作用機制
Mercaptopurine is an inactive prodrug that requires intracellular activation to exert its cytotoxic and immunosuppressive effects.
- Mercaptopurine enters the cell and is converted by the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) → thioinosinic acid (TIMP).
- TIMP acts as a purine antagonist, inhibiting multiple enzymes required for de novo purine synthesis.
- False nucleotides are incorporated into DNA and RNA → inhibition of nucleic acid synthesis → cell cycle arrest and apoptosis.
- It primarily affects rapidly dividing cells, strongly inhibiting humoral immunity (B-cell function) and, to a lesser extent, cell-mediated immunity.
安全性與警告
禁忌症
- Hypersensitivity to mercaptopurine
- Pregnancy (teratogenic and mutagenic)
不良反應
- Nausea
- Anorexia
- Vomiting
- Diarrhea
- Bone marrow suppression (leukopenia, thrombocytopenia, anemia)
- Hepatotoxicity
- Pancreatitis
- Gastrointestinal ulceration (including oral ulcers)
- Dermatologic reactions
注意事項
Risk vs. Benefit Warning: Use with extreme caution in patients with pre-existing hepatic dysfunction, bone marrow depression, active infections, renal function impairment (dosage adjustment required), or a history of urate urinary stones.
- Teratogenicity: Mercaptopurine is mutagenic and teratogenic (FDA Category D). Do not use in pregnant animals unless the benefit strictly outweighs the risk.
- Nursing: Unknown if excreted in milk; use milk replacer for nursing bitches or queens.
- Laboratory Interference: May cause falsely elevated serum glucose and uric acid values on SMA 12/60 analyzers.
藥物相互作用
Decreases hepatic metabolism of mercaptopurine via xanthine oxidase inhibition. Dose of mercaptopurine must be drastically reduced (to 1/4-1/3 of usual dose) if used concurrently.
May increase the risk for mercaptopurine toxicity.
Increased risk of hepatotoxicity; use cautiously together.
Increased risk of severe infection due to additive immunosuppression.
Additive bone marrow depression; use with extreme caution.
Increased risk of vaccine-induced infection; use with caution or avoid during therapy.
Mercaptopurine may reduce the anticoagulant effect of warfarin.
監測
- Hemograms (including platelets): Monitor closely; initially every 1-2 weeks, then every 1-2 months on maintenance therapy. (Note: If WBC drops to 5,000-7,000 cells/mm3, consider reducing dose by 25%. If WBC drops below 5,000 cells/mm3, discontinue until leukopenia resolves).
- Liver function tests (ALT, AST, ALP, Bilirubin)
- Serum amylase (if pancreatitis is suspected)
- Clinical efficacy and signs of toxicity
藥物動力學
吸收
Variable and incomplete after oral dosing.
分佈
Distributed throughout total body water. Crosses the blood-brain barrier, but not in levels significant enough to treat CNS neoplasms. Unknown if it enters milk.
代謝
Rapidly metabolized in the liver via the enzyme xanthine oxidase to 6-thiouric acid.
排除
Principally excreted in the urine as the parent compound and metabolites.
過量
Toxicity may present acutely (severe GI effects like vomiting and diarrhea) or be delayed (bone marrow depression, hepatotoxicity, gastroenteritis).
- Treatment: If ingestion was recent, use standard protocols to empty the GI tract (emesis, activated charcoal). Provide aggressive supportive care (IV fluids, antiemetics, broad-spectrum antibiotics if neutropenic, and potentially blood transfusions for severe myelosuppression).
可用產品
劑型
- Tablets
人用標示
- Mercaptopurine Tablets: 50 mg; Purinethol® (Gate Pharmaceuticals); generic (Par)
各地核准狀態
暫無法規資料: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Store tablets at room temperature in well-closed containers.
飼主須知
- 安全處理：這是一種強效的免疫抑制與抗癌藥物。給藥後請務必徹底洗手。孕婦或免疫力低下者應避免接觸此藥物。
- 觀察毒性反應：如果您的寵物出現異常出血、瘀青、食慾不振、嘔吐、腹瀉或感染跡象（如發燒或極度嗜睡），請立即聯繫您的獸醫。
- 嚴格監測：您的寵物需要頻繁進行血液檢查，以確保藥物沒有損害其骨髓或肝臟。請勿錯過這些回診。
- 長期風險：請注意，長期使用免疫抑制劑會帶來嚴重毒性的風險，包括增加感染的易感性或引發繼發性癌症。
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