麥角鈣化醇 (維生素D2)
Ergocalciferol
Vitamin D2, Calciferol, activated ergosterol
別名: Drisdol · Calciferol Drops · Vitamin D2 · Viosterol · Activated ergosterol · Irradiated ergosterol
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 |
|---|---|---|---|---|---|
| Maintenance therapy of parathyroid failure after using parenteral calcium to control hypocalcemic tetany | Initially 4000-6000 Units/kg PO once daily. Maintenance doses usually range from 1000-2000 Units/kg PO once daily to once weekly. | PO | once daily to once weekly | Lifelong | 🌎 NA |
- Maintenance therapy of parathyroid failure after using parenteral calcium to control hypocalcemic tetany: Patient should be hospitalized initially. Adjust dosage to maintain serum calcium concentrations between 8-9.5 mg/dL. Goal is to prevent hypocalcemic tetany, but not induce hypercalcemia.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Maintenance therapy of parathyroid failure after using parenteral calcium to control hypocalcemic tetany | Initially 4000-6000 Units/kg PO once daily. Maintenance doses usually range from 1000-2000 Units/kg PO once daily to once weekly. | PO | once daily to once weekly | Lifelong | 🌎 NA |
- Maintenance therapy of parathyroid failure after using parenteral calcium to control hypocalcemic tetany: Patient should be hospitalized initially. Adjust dosage to maintain serum calcium concentrations between 8-9.5 mg/dL. Goal is to prevent hypocalcemic tetany, but not induce hypercalcemia.
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
麥角鈣化醇 (Ergocalciferol, 維生素D2) 是一種脂溶性維生素及維生素D類似物，主要用於獸醫學中治療與甲狀旁腺功能低下相關的低血鈣症。
- 具成本效益：通常作為骨化三醇 (Calcitriol) 或雙氫速甾醇 (DHT) 的較廉價替代品。
- 起效較慢：因為它需要肝臟和腎臟的酵素活化，與活性代謝物相比，需要較長時間（5-21天）才能對血清鈣產生最大影響。
- 毒性持久：具有高度脂溶性並儲存於脂肪中。如果發生高血鈣症，即使停藥，毒性作用也可能持續長達18週。
臨床要點：與膽鈣化醇 (維生素D3) 相比，貓無法有效地將麥角鈣化醇轉化為其25-羥基化形式。因此，在治療貓的低血鈣症時，通常首選骨化三醇。
作用機轉
Ergocalciferol is an inactive prodrug that requires a two-step enzymatic activation process to regulate calcium homeostasis:
- Ergocalciferol → hepatic 25-hydroxylase → 25-hydroxyvitamin D2 (calcidiol, partially active).
- 25-hydroxyvitamin D2 → renal 1-alpha-hydroxylase → 1,25-dihydroxyvitamin D2 (fully active calcitriol equivalent).
The active metabolite binds to intracellular Vitamin D Receptors (VDR), acting as a hormone alongside parathyroid hormone (PTH) and calcitonin to:
- Enhance intestinal absorption of calcium and phosphate.
- Promote renal tubular reabsorption of calcium.
- Increase the rate of accretion and osteoclastic resorption of minerals in bone, mobilizing calcium into the extracellular fluid.
安全性與警告
禁忌症
- Hypercalcemia
- Vitamin D toxicity
- Malabsorption syndrome
- Abnormal sensitivity to the effects of vitamin D
不良反應
- Hypercalcemia
- Hyperphosphatemia
- Nephrocalcinosis
- Soft tissue mineralization
注意事項
Important Warnings
- Renal Impairment: Patients with kidney dysfunction may not convert ergocalciferol into the primary active metabolite. Calcitriol or DHT is preferred as they bypass renal activation.
- Hyperphosphatemia: Use with extreme caution. Elevated calcium and phosphorus simultaneously can lead to severe metastatic soft tissue mineralization (monitor calcium x phosphorus product).
- Monitoring Commitment: Chronic therapy should not be initiated unless owners are willing to commit to ongoing, rigorous patient monitoring.
- Pregnancy: Hypervitaminosis D has been implicated in causing teratogenic effects. Weigh potential benefits against risks.
- Nursing: Large doses of vitamin D are excreted into milk. Consider using milk replacer for offspring of dams receiving therapeutic dosages.
藥物交互作用
Can reduce the effects of vitamin D analogs by decreasing calcium absorption and increasing renal excretion.
Patients are highly sensitive to the arrhythmogenic effects of hypercalcemia; intensified monitoring is required.
Patients are sensitive to the effects of hypercalcemia; intensified monitoring is required.
May reduce the amount of orally administered ergocalciferol absorbed from the GI tract.
May cause hypercalcemia when given in conjunction with Vitamin D analogs due to decreased renal calcium excretion.
監測
- Serum calcium concentrations (weekly initially, then monthly for 6 months, then every 2-3 months)
- Serum phosphorus concentrations
- Renal function parameters (BUN, Creatinine)
- Clinical signs of hypercalcemia (PU/PD, lethargy, anorexia, vomiting)
藥物動力學
吸收
Absorbed from the small intestine in the presence of bile salts.
分佈
Stored extensively in the liver and fat. Several days of therapy may be required until distribution steady state is achieved.
代謝
Hydroxylated in the liver to 25-hydroxyvitamin D, then activated in the kidneys to 1,25-dihydroxyvitamin D. Cats do not appear to convert ergocalciferol to its 25-hydroxylate form as well as cholecalciferol.
排除
Effects may persist for up to 18 weeks once treatment is discontinued due to slow release from fat stores.
過量
Acute Toxicity
- The toxic acute oral dose of ergocalciferol in dogs is reported as 4 mg/kg (160,000 Units/kg).
- Decontamination: Acute ingestions should be managed using established protocols for removal or prevention of GI absorption. Orally administered mineral oil may reduce absorption and enhance fecal elimination.
Chronic Overdosage (Hypercalcemia)
- Immediate Action: Temporarily discontinue ergocalciferol and any exogenous calcium therapy.
- Medical Management: If hypercalcemia is severe, administer 0.9% normal saline (calcium-free IV fluids), furosemide (to promote calciuresis), and corticosteroids (to decrease GI absorption and increase renal excretion of calcium). Urine acidification may also be employed.
- Prolonged Effect: Because of the long duration of action (potentially up to 18 weeks), hypercalcemia may persist for weeks to months. Restart therapy at a reduced dosage only when calcium serum levels return to the normal range.
可用產品
劑型
- Oral Liquid (Drops)
- Oral Capsules
人用標示
- Ergocalciferol Oral Liquid (Drops): 8,000 Units/mL (200 micrograms/mL) in 60 mL
- Ergocalciferol Oral Capsules: 50,000 Units (1.25 mg)
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
Ergosterol is sensitive to light, heat, and air. Store capsules or liquid at room temperature (15-30°C) and protect from light.
飼主須知
- 成本與療效：雖然麥角鈣化醇比其他維生素D藥物（如骨化三醇）便宜，但通常不作為首選，因為它需要較長時間才能發揮作用，且在體內停留的時間更長。
- 終身治療：使用維生素D產品治療甲狀旁腺問題通常需要終身服藥，並定期回診進行血液檢查。
- 高血鈣風險：雖然此藥物可以治療低血鈣，但過量會導致血鈣濃度危險地升高。由於藥物儲存在體脂肪中，即使停藥，這種毒性副作用也可能持續數週。
- 注意症狀：如果您的寵物出現高血鈣症狀，如劇烈口渴、排尿增加、嘔吐或極度疲倦，請立即聯繫您的獸醫師。
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