葉酸
Folic Acid
Pteroylglutamic acid
別名: Folvite · Deplin · Folate · Folacin · Vitamin B9 · Acidum folicum · Pteroylglutamic acid · Pteroylmonoglutamic acid · Vitamin B11
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 |
|---|---|---|---|---|---|
| Severe folate deficiency | 0.5-2 mg (total dose) PO once daily | PO | q24h | 1 month | 🌎 NA |
| Folate and cobalamin deficiency secondary to inflammatory bowel disease | 5 mg (total dose) PO once daily | PO | q24h | 1-6 months | 🌎 NA |
- Folate and cobalamin deficiency secondary to inflammatory bowel disease: Given with cyanocobalamin 750 micrograms parenterally once per month.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Severe folate deficiency | 0.5-2 mg (total dose) PO once daily | PO | q24h | 1 month | 🌎 NA |
| Folate deficiency secondary to exocrine pancreatic insufficiency | 400 micrograms (0.4 mg) PO once daily | PO | q24h | — | 🌎 NA |
| Long-term use of high dose trimethoprim/sulfa (for treating Nocardia) | 2 mg (total dose) PO once daily | PO | q24h | — | 🌎 NA |
| Adjunctive therapy in cats with inflammatory bowel disease | 0.5-1 mg PO q24h (once daily) | PO | q24h | 4-6 weeks | 🌎 NA |
- Adjunctive therapy in cats with inflammatory bowel disease: Given with cobalamin at 125-250 micrograms SC or IM once a week.
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Prolonged therapy with antifolate medications (e.g., trimethoprim, pyrimethamine) | 20-40 mg (total dose) PO per day | PO | q24h | — | 🌎 NA |
- Prolonged therapy with antifolate medications (e.g., trimethoprim, pyrimethamine): Pregnant mares should routinely receive folic acid supplementation during treatment with antifolates.
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
葉酸（維生素 B9）是一種重要的水溶性維生素，對於核蛋白合成和正常的紅血球生成至關重要。
在獸醫學中，它主要用於治療葉酸缺乏症，這通常繼發於胃腸道疾病。
臨床要點與診斷效用：
- 吸收部位： 葉酸專門在近端小腸吸收，而鈷胺素（維生素 B12）則在遠端小腸吸收。
- 診斷指標： 測量血清葉酸和鈷胺素有助於定位腸道疾病。葉酸偏低通常暗示近端小腸疾病。
- 細菌過度生長： 患有胰腺外分泌不足 (EPI) 或小腸細菌過度生長 (SIBO) 的犬隻，其血清葉酸通常會升高，因為腸道細菌會合成葉酸。
- 抗葉酸藥物救援： 它也用於預防或治療因長期使用二氫葉酸還原酶抑制劑（例如：甲氧苄啶、乙胺嘧啶）所引起的缺乏症。
作用機轉
Folic acid is a precursor that must be enzymatically reduced to become biologically active.
Mechanism Pathway: Folic Acid → reduced by dihydrofolate reductase (DHFR) → Tetrahydrofolate (THF / 5-methyltetrahydrofolate).
- THF acts as a crucial coenzyme and methyl donor in the synthesis of purine and pyrimidine nucleotides.
- This pathway is absolutely necessary for DNA synthesis, cellular division, and the maintenance of normal erythropoiesis.
- Drugs like trimethoprim and methotrexate competitively inhibit DHFR, blocking this pathway and potentially causing megaloblastic anemia or leukopenia, which is why folic acid supplementation is used as a rescue therapy.
安全性與警告
禁忌症
- Known intolerance or hypersensitivity to folic acid
- Undiagnosed anemias (folic acid therapy may mask the hematologic signs of pernicious anemia/cobalamin deficiency while neurologic damage progresses)
不良反應
- Hypersensitivity reactions (rare)
- Gastrointestinal effects (rare)
- CNS effects such as difficulty sleeping, excitement, or confusion (seen only at very high oral doses in humans, e.g., 15 mg/day)
注意事項
Important: Do not administer therapeutic doses of folic acid to dogs with enteropathies until baseline serum folate and cobalamin levels have been determined, as dogs may have increased, normal, or decreased folate levels depending on the specific disease process (e.g., bacterial overgrowth vs. malabsorption).
- Prolonged folic acid supplementation can potentially decrease serum cobalamin (B-12) levels.
- Folic acid is considered very safe during pregnancy (FDA Category A) and lactation. Requirements may actually increase in lactating animals.
藥物交互作用
May delay the hematologic response to folic acid.
Inhibits dihydrofolate reductase; interferes with folic acid utilization.
Inhibits dihydrofolate reductase; interferes with folic acid utilization.
Inhibits dihydrofolate reductase; interferes with folic acid utilization.
Folic acid may decrease serum phenytoin levels, potentially requiring a dosage increase; increased seizure frequency can occur.
May increase the risk for folate deficiency.
May increase the risk for folate deficiency.
May increase the risk for folate deficiency.
May increase the risk for folate deficiency.
監測
- Serum folate and cobalamin levels (before and after treatment)
- Clinical signs associated with deficiency (e.g., chronic diarrhea, weight loss)
- CBC (baseline and ongoing if abnormal, to monitor for anemia)
藥物動力學
吸收
Primarily absorbed in the proximal small intestine via carrier-mediated diffusion. Synthetic folic acid is nearly completely absorbed after oral administration, while folate in foodstuffs is about 50% bioavailable.
分佈
Distributed widely throughout the body and stored in the liver. Erythrocyte and CSF levels can be significantly higher than serum levels. Undergoes enterohepatic recirculation.
代謝
Converted to its active form, tetrahydrofolic acid, principally in the liver and plasma.
排除
Excreted primarily in the urine either as metabolites or unchanged drug (when administered in excess of body requirements).
過量
Folic acid is relatively non-toxic.
If an inadvertent overdose occurs, no specific treatment should be required. Excess drug is rapidly metabolized or excreted unchanged in the urine.
可用產品
劑型
- Tablets
- Injection
獸醫用
- None as sole ingredient products. (Available in various multivitamin combinations)
人用標示
- Folic Acid Tablets: 0.4 mg, 0.8 mg (OTC); 1 mg, 7.5 mg, 15 mg (Rx)
- Deplin® (Pamlab)
- Folic Acid Injection: 5 mg/mL in 10 mL vials (Folvite®, generic) (Rx)
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 in well-closed containers below 40°C (104°F), preferably between 15-30°C; protect from light and moisture. Store injection protected from light below 40°C (104°F); do not freeze.
飼主須知
- 用途： 葉酸是一種 B 群維生素，用於治療通常由慢性腸道疾病、胰腺問題或長期使用某些抗生素引起的缺乏症。
- 安全性： 它是一種非常安全的補充劑。因為它是水溶性的，身體很容易將多餘的量從尿液中排出。
- 給藥方式： 可以與食物一起或空腹給予。請仔細遵循獸醫的指示。
- 長期護理： 如果您的寵物患有慢性腸道疾病或胰腺外分泌不足，可能需要終身監測維生素水平並定期進行補充治療，以保持牠們的健康。
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