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美替拉酮

Metyrapone

2-methyl-1,2-di(pyridin-3-yl)propan-1-one

腎上腺類固醇抑制劑PO貓

別名: Metopirone · SU-4885 · metirapona · metyraponum

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

65 mg/kg PO every 8 to 12 hoursPO· q8-12h
— 🐈

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

貓

適應症劑量途徑頻次療程地區
Hyperadrenocorticism65 mg/kg PO every 8 to 12 hoursPOq8-12h—🌎 NA
  • Hyperadrenocorticism: Alternatively, dosages ranging from 195-250 mg/cat/day (divided) have been used without observed toxicity (Bruyette 2010).

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。

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概覽

美替拉酮是一種​腎上腺類固醇合成抑制劑​，在獸醫學中主要用於控制貓的腎上腺皮質機能亢進（庫興氏症候群）。

  • ​臨床用途​：最常用於外科手術（腎上腺切除術）前的短期醫療穩定治療。
  • ​併發糖尿病​：貓的庫興氏症候群較罕見，且常伴隨具胰島素阻抗的糖尿病。藉由解決皮質醇過高的問題，美替拉酮能減少胰島素拮抗作用，從而顯著降低甚至消除對外源性胰島素的需求。
  • ​物種特異性​：雖然臨床經驗有限，但貓對此藥物的耐受性似乎良好。它也可能對雪貂和小型哺乳動物（如倉鼠）有效，但缺乏這些物種的藥代動力學和安全性數據。
  • ​人類用途​：在人類醫學中，它被用於診斷評估下視丘-腦下垂體-腎上腺 (HPA) 軸的功能，以及標示外用於治療庫興氏症候群。

作用機制

Metyrapone exerts its effects by directly interfering with the steroidogenic pathway within the adrenal cortex:

  • Enzyme Inhibition: It reversibly inhibits the enzyme 11-β-hydroxylase (CYP11B1).
  • Pathway Blockade: 11-deoxycortisol → [Blocked by Metyrapone] → Cortisol. This prevents the final hydroxylation step, leading to a rapid reduction in circulating cortisol and corticosterone levels.
  • Feedback Loop: The sudden drop in cortisol removes negative feedback on the pituitary gland, leading to a compensatory surge in ACTH secretion. Over time, this ACTH surge can override the enzymatic blockade, limiting the drug's long-term efficacy.
  • Mineralocorticoid Effects: It can also suppress aldosterone synthesis, causing mild natriuresis. However, long-term use leads to the accumulation of 11-desoxycorticosterone (a precursor with mineralocorticoid activity), which prevents Addisonian crises but can induce hypertension.

安全性與警告

禁忌症

  • Known hypersensitivity to metyrapone
  • Primary adrenal cortical insufficiency (Addison's disease)

不良反應

  • Nausea
  • Vomiting
  • Abdominal pain
  • Headache (reported in humans)
  • Dizziness (reported in humans)
  • Sedation (reported in humans)
  • Allergic rash (reported in humans)
  • Bone marrow depression (rare)

注意事項

Diabetic Patients: Use with extreme caution and enhanced monitoring in cats with concurrent diabetes mellitus. As cortisol levels drop, insulin resistance resolves, and hypoglycemia can develop rapidly if insulin doses are not adjusted.

  • Pregnancy: FDA Category C. Use in pregnant queens only if clearly needed. Fetal pituitary response to the enzymatic block has been detected in humans.
  • Lactation: Safety is unknown; use with caution.
  • Laboratory Interference: May interfere with diagnostic tests. Antidepressants, antithyroid drugs, phenothiazines, barbiturates, and exogenous hormones can alter metyrapone test results.

藥物相互作用

Acetaminophen

Increased risk for acetaminophen toxicity. Note: Acetaminophen is strictly contraindicated in cats due to fatal methemoglobinemia and hepatotoxicity.

Corticosteroids

Decreases the efficacy of metyrapone by suppressing ACTH and interfering with the diagnostic or therapeutic intent.

監測

  • Blood glucose levels (critical in diabetic cats)
  • Clinical signs of hyperadrenocorticism (to assess efficacy)
  • Clinical signs of hypoadrenocorticism/Addisonian crisis (lethargy, vomiting, collapse)
  • Electrolytes (sodium, potassium)

藥物動力學

吸收

In humans, well absorbed after oral administration. Peak plasma levels occur in about 1 hour, though pharmacological response is delayed.

分佈

Rapidly cleared from the plasma.

代謝

Reduced to an active metabolite, metyrapol. In humans, both parent drug and metabolite are conjugated with glucuronide. Because cats are deficient in glucuronidation pathways, the exact metabolic fate in felines is unclear.

排除

In humans, the average elimination half-life is approximately 2 hours. The active metabolite (metyrapol) has a half-life roughly twice as long.

過量

Acute toxicity data indicates an oral LD50 in rats of 521 mg/kg.

Clinical Signs of Overdose:

  • Gastrointestinal distress (severe vomiting/nausea)
  • ​Acute adrenocortical insufficiency (Addisonian crisis)​
  • Hypoglycemia, hyponatremia, hypochloremia, hyperkalemia
  • Cardiac arrhythmias, hypotension, dehydration, and altered mentation

Treatment:

  • No specific antidote exists.
  • Standard gastrointestinal decontamination protocols if ingestion is recent.
  • Intravenous fluid therapy (saline) supplemented with glucose.
  • Administration of intravenous hydrocortisone or dexamethasone to replace depleted corticosteroids.
  • Intensive monitoring and supportive care for several days may be required.

可用產品

劑型

  • Oral capsules
  • Compounded oral suspensions or capsules (veterinary)

人用標示

  • Metyrapone Oral Capsules: 250 mg; Metopirone® (Ciba-Geigy); (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 at room temperature in a well-closed, light-resistant container.

飼主須知

​重要提示​：此藥物用於降低貓咪體內產生的皮質醇（壓力荷爾蒙）量。因為通常需要根據貓咪的體型進行客製化調配（複方），請務必仔細遵循藥局的保存指示。

  • ​給藥方式​：請將此藥物與食物一起餵食，以減少胃部不適和嘔吐的機會。
  • ​糖尿病貓咪​：如果您的貓咪同時在接受胰島素治療，請密切觀察。當此藥物發揮作用時，貓咪對胰島素的需求可能會大幅下降，從而增加低血糖的風險。請注意是否有虛弱、步態不穩或癲癇發作的症狀。
  • ​何時該聯絡獸醫師​：如果您的貓咪出現食慾不振、異常虛弱或缺乏活力、嘔吐、腹瀉，或飲水及排尿習慣改變，請​立即​聯絡您的獸醫師。這些可能是皮質醇濃度降得太低的徵兆。

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