亞葉酸鈣
Leucovorin Calcium
5-formyl tetrahydrofolic acid
別名: Citrovorum factor · 5-formyl tetrahydrofolate · citrovorin · folidan · FTHF · NSC-3590 · calcium folinate · calcifolin · calfonat · folinic acid calcium salt
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 |
|---|---|---|---|---|---|
| Folate deficiency associated with pyrimethamine use | 5-15 mg (total dose) PO or parenterally once daily | PO/Parenteral | q24h | — | 🌎 NA |
| Methotrexate overdose | 25-200 mg/m2 parenterally every 6 hours until methotrexate levels are less than 1 X 10 -8 M | Parenteral | q6h | Until methotrexate levels are < 1 X 10^-8 M | 🌎 NA |
- Methotrexate overdose: Most effective if given within 48 hours of overdose. Dose is dependent on serum methotrexate concentration.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Folate deficiency associated with pyrimethamine use | 5-15 mg (total dose) PO or parenterally once daily | PO/Parenteral | q24h | — | 🌎 NA |
| Bone marrow suppression associated with pyrimethamine or trimethoprim/sulfa | 5 mg once daily | Not specified | q24h | — | 🌎 NA |
| To prevent bone marrow toxicity associated with pyrimethamine | 1 mg/kg once daily | Not specified | q24h | — | 🌎 NA |
| Methotrexate overdose | 25-200 mg/m2 parenterally every 6 hours until methotrexate levels are less than 1 X 10 -8 M | Parenteral | q6h | Until methotrexate levels are < 1 X 10^-8 M | 🌎 NA |
- Methotrexate overdose: Most effective if given within 48 hours of overdose.
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Macrocytic anemia and neutropenia associated with pyrimethamine and/or trimethoprim (especially in pregnant mares) | 0.1-0.3 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
- Macrocytic anemia and neutropenia associated with pyrimethamine and/or trimethoprim (especially in pregnant mares): A more practical approach would be to ensure that the horse receives green hay or pasture (high tetrahydrofolate levels in green roughage).
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
亞葉酸鈣（Leucovorin calcium，又稱甲醯四氫葉酸 folinic acid）是一種還原型的葉酸衍生物，在獸醫學中主要作為救援劑或解毒劑。
- 主要適應症：用於逆轉或預防由二氫葉酸還原酶抑制劑（如乙胺嘧啶 pyrimethamine、甲氧苄啶 trimethoprim 或 奧美普林 ormetoprim）引起的血液毒性（如骨髓抑制、巨紅血球性貧血和嗜中性白血球低下）。
- 甲氨蝶呤救援：雖然在人類醫學中常規用作高劑量甲氨蝶呤（methotrexate）化療的救援劑，但在獸醫學中極少用於此目的，除非發生意外的甲氨蝶呤中毒。
- 臨床要點：與一般葉酸不同，亞葉酸鈣不需要經過二氫葉酸還原酶的轉換即可具有生物活性。這使其能夠繞過葉酸拮抗劑造成的酵素阻斷，直接提供細胞功能所需的葉酸。
作用機轉
Leucovorin is a reduced form of folic acid that acts as a direct coenzyme in cellular metabolism.
- Bypassing DHFR: It does not require conversion by dihydrofolate reductase (DHFR) to become biologically active.
- Active Metabolite: It is converted in the body to active reduced forms, predominantly 5-methyltetrahydrofolate (5-methyl THF).
- DNA Synthesis: These reduced folates act as coenzymes in the synthesis of purine and pyrimidine nucleotides → essential for DNA synthesis and the maintenance of normal erythropoiesis (red blood cell production).
- Enzyme Inhibition: Leucovorin inhibits thymidylate synthase by stabilizing the binding of fluorodeoxyuridylic acid to the enzyme. This mechanism potentiates both the antineoplastic activity and the toxicity of fluorouracil (5-FU).
安全性與警告
禁忌症
- Known intolerance or hypersensitivity to leucovorin
不良反應
- Gastrointestinal effects (noted in humans with oral administration)
- Seizures (very rare, noted in humans)
- Hypersensitivity reactions (very rare, noted in humans)
注意事項
Use with extreme caution in patients receiving systemic fluorouracil. Because of its calcium content, large intravenous doses should be given slowly and not bolused. In humans, folinic acid therapy may mask the signs associated with cobalamin (B-12) deficiency in megaloblastic anemias. When reconstituting powder with bacteriostatic water (which contains benzyl alcohol), avoid use in neonates or very small animals.
藥物交互作用
Large doses of leucovorin may reduce the antiseizure efficacy of these agents.
Leucovorin may increase both the antineoplastic efficacy and toxicity of 5-FU.
Leucovorin may reduce their efficacy somewhat; however, protozoa cannot utilize leucovorin, preserving the antimicrobial effect against them.
監測
- Complete Blood Count (CBC)
- Methotrexate serum levels (if used for methotrexate overdoses; may require contacting a local human hospital)
藥物動力學
半衰期
吸收
In humans, oral bioavailability is dose-dependent (97% at 25 mg, decreasing to 37% at 100 mg). IM bioavailability is similar to IV. Peak levels of active reduced folates occur 1.7-2.4 hours after oral dosing, and about 10 minutes after IV administration.
分佈
Apparent volume of distribution for both L- and D-forms is about 0.6 L/kg in dogs. About 50% of oral body stores of reduced folates are found in the liver.
代謝
Extensively metabolized to active reduced forms, predominantly 5-methyltetrahydrofolate (5-methyl THF).
排除
Excreted into the urine, primarily as 10-formyl-THF or 5,10-methyl-THF.
過量
Except in situations where drug interactions are possible (e.g., with fluorouracil or antiseizure medications), an inadvertent overdose is unlikely to be of clinical concern.
可用產品
劑型
- Oral tablets
- Injection solution
- Powder for injection
人用標示
- Leucovorin Calcium Oral Tablets: 5 mg, 15 mg, & 25 mg
- Leucovorin Calcium Injection Solution: 10 mg/mL in 5 mg single dose vials
- Leucovorin Calcium Powder for Injection: 50 mg, 100 mg, 200 mg & 350 mg in vials
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
Tablets and powder for injection should be stored below 40°C (preferably between 15-30°C) in a well-closed container and protected from light. Injection solution should be refrigerated between 2-8°C and protected from light. Reconstituted solutions made with sterile water should be used immediately; those made with bacteriostatic water are stable up to 7 days. IV solutions in LRS, Ringer's, or 0.9% NaCl are stable up to 24 hours at room temperature. Not compatible with fluorouracil solutions.
飼主須知
重要提示：如果您的寵物是因為甲氨蝶呤（methotrexate）中毒而使用此藥物，必須在動物醫院內由獸醫嚴密監控下住院給藥。
- 給藥方式：口服亞葉酸鈣可以與食物一起或空腹服用。
- 嚴格遵守用藥時間：務必完全按照獸醫指示的劑量和時間表給藥。錯過劑量可能會影響嚴重血液毒性的預防或治療效果。
- 忘記服藥：如果漏餵了一劑，請聯繫您的獸醫獲取指示。在沒有專業指導的情況下，請勿自行將劑量加倍。
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