氟胞嘧啶
Flucytosine
5-fluorocytosine
別名: Ancobon · Ancotil · Alcobon · 5-FC · 5-fluorocytosine · flucytosinum · Ro-2-9915
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 |
|---|---|---|---|---|---|
| Cryptococcosis | 50-75 mg/kg PO q8h | PO | q8h | 1-12 months | 🌎 NA |
| Candidiasis | 25-50 mg/kg PO q6h or 50-65 mg/kg PO q8h | PO | q6h or q8h | 42 days | 🌎 NA |
- Cryptococcosis: Must be given with a polyene or azole antifungal agent.
- Candidiasis: Must be given with a polyene or azole antifungal agent.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Cryptococcosis | 30 mg/kg PO q6h or 50 mg/kg PO q8h or 75 mg/kg PO q12h | PO | q6h, q8h, or q12h | 1-9 months | 🌎 NA |
| Candidiasis | 25-50 mg/kg PO q6h or 50-65 mg/kg PO q8h | PO | q6h or q8h | 42 days | 🌎 NA |
- Cryptococcosis: Cats 3.5 kg or greater should receive 250 mg (total) q6-8h. Must be given with a polyene (amphotericin B) or azole antifungal agent.
- Candidiasis: Must be given with a polyene or azole antifungal agent.
鳥
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Susceptible fungal infections (Psittacines) | 250 mg/kg twice daily as a gavage | PO | q12h | Extended periods | 🌎 NA |
| Susceptible fungal infections (Raptors) | 18-30 mg/kg q6h as a gavage | PO | q6h | — | 🌎 NA |
| Susceptible fungal infections (Psittacines and Mynahs) | 100-250 mg/lb in feed | PO | Continuous | — | 🌎 NA |
| Susceptible fungal infections (Ratites) | 80-100 mg/kg PO twice daily | PO | q12h | — | 🌎 NA |
- Susceptible fungal infections (Psittacines): May cause bone marrow toxicity; periodic hematologic assessment is recommended.
- Susceptible fungal infections (Psittacines and Mynahs): For flock treatment of severe aspergillosis or Candida. Apply to favorite food mix or mixed with mash.
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
氟胞嘧啶（Flucytosine，又稱 5-FC）是一種氟化嘧啶類抗黴菌藥物，主要對隱球菌 (Cryptococcus) 和念珠菌 (Candida) 具有活性。
關鍵臨床重點：
- 必須合併治療： 單獨使用時，黴菌極易產生抗藥性（尤其是隱球菌）。因此幾乎完全與兩性黴素 B (Amphotericin B) 或唑類 (Azole) 抗黴菌藥物合併使用以產生協同作用。
- 中樞神經穿透力： 該藥物能極佳地穿透血腦屏障，在治療中樞神經系統隱球菌症方面具有高度價值。
- 毒性疑慮： 具有劑量依賴性的骨髓抑制風險。犬隻特別敏感，若治療超過 10-14 天可能會出現嚴重的藥物不良反應。
- 物種差異： 哺乳動物細胞通常缺乏將氟胞嘧啶轉化為毒性代謝物 (5-氟尿嘧啶) 的酵素，但腸道菌叢或特定物種的代謝（如大鼠）可能導致全身性毒性。
作用機轉
Flucytosine acts as a prodrug that exploits specific fungal enzymes:
- Cellular Entry: Flucytosine enters the fungal cell via the enzyme cytosine permease.
- Conversion to Active Metabolite: Inside the fungal cell, it is deaminated by cytosine deaminase → 5-fluorouracil (5-FU). (Note: Human and most mammalian cells lack this enzyme, providing selective toxicity).
- RNA Inhibition: 5-FU acts as an antimetabolite, competing with uracil → incorporates into fungal RNA → disrupts pyrimidine metabolism and halts protein synthesis.
- DNA Inhibition: 5-FU is also converted to fluorodeoxyuridylic acid → potently inhibits thymidylate synthetase → halts DNA synthesis and cell division.
安全性與警告
禁忌症
- Known hypersensitivity to flucytosine
不良反應
- Gastrointestinal disturbances (nausea, vomiting, diarrhea)
- Dose-dependent bone marrow depression (anemia, leukopenia, thrombocytopenia)
- Cutaneous eruption and rash (primarily on scrotum and nasal planum in dogs)
- Oral ulceration
- Increased hepatic enzymes
- Severe drug reaction in dogs within 10-14 days of treatment
- Aberrant behavior and seizures (reported in cats)
- Toxic epidermal necrolysis (anecdotal in cats)
注意事項
Extreme Caution: Use with extreme care in patients with renal impairment, as the drug is renally excreted. Dosage intervals must be adjusted based on creatinine clearance to prevent toxic accumulation.
- Hematologic Risk: Use with extreme caution in patients with preexisting bone marrow depression, hematologic diseases, or those receiving other bone marrow suppressant drugs.
- Hepatic Disease: Use cautiously with enhanced monitoring in patients with liver disease.
- Pregnancy: Teratogenic in rats (FDA Category C). Use only when benefits outweigh risks. Consider milk replacer for nursing offspring.
- Laboratory Interference: May cause false elevations in serum creatinine levels when using the Ektachem® analyzer.
藥物交互作用
Synergistic antifungal efficacy against Cryptococcus and Candida. However, amphotericin B-induced nephrotoxicity can decrease flucytosine excretion, leading to flucytosine accumulation and enhanced bone marrow toxicity. Dosage adjustments and strict monitoring are required.
監測
- Renal function (BUN, Creatinine, Urinalysis) - at least twice weekly if also receiving amphotericin B
- CBC with platelets (to monitor for bone marrow suppression)
- Hepatic enzymes (at least monthly)
- Serum flucytosine levels (target < 100 mcg/mL) in patients with renal impairment, if available
藥物動力學
吸收
Well absorbed after oral administration. The rate, but not the extent, of absorption is decreased if given with food.
分佈
Distributed widely throughout the body. Penetrates the CNS well, with CSF concentrations reaching 60-100% of serum levels. Volume of distribution is ~0.7 L/kg in healthy humans. Only 2-4% is bound to plasma proteins.
代謝
Minimal metabolism in humans. Rats metabolize some of the drug to fluorouracil (explaining teratogenic effects). The extent of cytosine deaminase activity in dog and cat cells is unclear.
排除
Excreted basically unchanged in the urine via glomerular filtration.
過量
Specific information regarding flucytosine overdosage in veterinary species is limited.
Management:
- For substantial acute overdoses, standard gastrointestinal decontamination (gut emptying, activated charcoal, and cathartic administration) is recommended unless contraindicated.
- Monitor hematologic and renal parameters closely, providing supportive care as needed.
可用產品
劑型
- Oral capsules
- Compounded oral suspension
人用標示
- Flucytosine Oral Capsules: 250 mg & 500 mg (Ancobon®)
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 capsules in tight, light-resistant containers at temperatures less than 40°C, preferably at room temperature (15-30°C). Compounded oral suspensions (10 mg/mL in Ora-Plus/Ora-Sweet) retain >95% potency for 60 days when stored at 5°C or 25°C.
飼主須知
了解藥物： 氟胞嘧啶是一種專門的抗黴菌藥物，用於治療嚴重的深層黴菌感染（如隱球菌症）。為了防止黴菌產生抗藥性，它幾乎總是與另一種抗黴菌藥物合併使用。
注意事項：
- 出血或瘀傷： 此藥物可能會抑制骨髓製造血球的能力。如果您發現寵物有異常出血、瘀傷、牙齦蒼白或極度疲倦，請立即聯繫您的獸醫師。
- 腸胃不適： 可能會出現噁心、嘔吐或腹瀉。如果這些症狀持續存在，請告知您的獸醫師。
- 皮膚變化： 在犬隻中，可能會出現皮疹或潰瘍，特別是在鼻部或陰囊上。
治療承諾： 治療深層黴菌感染需要極大的耐心與承諾。治療通常持續數個月，並且需要頻繁進行血液檢查，以確保藥物不會對您寵物的腎臟、肝臟或骨髓造成損害。
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