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甲硫胺酸

Methionine

DL-Methionine, Racemethionine

尿液酸化劑 / 營養補充劑POIVtopical狗貓馬牛

別名: Ammonil · Acimethin · Acimol · M-Caps · Methigel · Methio-Form · Methiotrans · Methnine · Neutrodor · Pedameth · Uracid · Uromethin · Uroeze · dl-methionine · racemethionine · s-methionine · methioninum

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

100 mg/kg PO q12hPO· q12h
— 🐕

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

狗

適應症劑量途徑頻次療程地區
Urine acidification (struvite dissolution)100 mg/kg PO q12hPOq12h—🌎 NA
Struvite dissolution therapy (if diet and antimicrobials do not result in acid urine)0.2-1 gram PO q8hPOq8h—🌎 NA
  • Urine acidification (struvite dissolution): Safe and effective in dissolving presumed infection-induced struvite uroliths in combination with an appropriate anti-microbial agent without using a struvite dissolution diet.

貓

適應症劑量途徑頻次療程地區
Urine acidification1000-1500 mg per day given in the food once dailyPOq24h—🌎 NA
Urine acidification0.2-1 gram PO once dailyPOq24h—🌎 NA
  • Urine acidification: Use if diet and antimicrobials do not reduce pH.

馬

適應症劑量途徑頻次療程地區
Laminitis (purported)22 mg/kg PO once daily for one week; then 11 mg/kg PO once daily for 1 week; then 5.5 mg/kg PO once daily for one weekPOq24h3 weeks🌎 NA
Senecio-induced liver damage12.5 grams IV in one liter saline/dextrose solutionIVOnce—🌎 NA

牛

適應症劑量途徑頻次療程地區
General / Ketosis20-30 grams POPO——🌎 NA

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

​甲硫胺酸 (Methionine)​ 是一種含硫的必需胺基酸，在獸醫學中主要用作​尿液酸化劑​和營養補充劑。

  • ​尿液酸化：​ 過去常被用於降低尿液 pH 值，以溶解並預防​磷酸銨鎂結石 (struvite)​。
  • ​臨床要點：​ 在小動物臨床上，其用途已大半被專業處方泌尿道飲食（如 s/d, c/d）所取代，這些飲食能有效控制尿液 pH 值而無需額外補充藥物。
  • ​抗脂肪肝劑：​ 作為抗脂肪肝劑，可預防或糾正因缺乏膽鹼引起的脂肪肝。
  • ​大型動物用途：​ 在豬和家禽中作為營養補充劑；用於治療牛的酮症；並被宣稱可用於治療馬和牛的蹄葉炎（理論上可提供雙硫鍵基質以維持蹄骨結合），但缺乏確切的療效證據。

作用機制

Methionine exerts its effects through several metabolic pathways:

  • ​Urine Acidification:​ Methionine is metabolized in the liver, where its sulfur component is oxidized to sulfate. This sulfate is excreted by the kidneys as sulfuric acid → effectively lowering urine pH.
  • ​Lipotropic Action:​ Methionine supplies methyl groups to ethanolamine → forms choline, which is essential for lipid transport and metabolism in the liver, preventing hepatic lipidosis.
  • ​Antioxidant & Structural Precursor:​ Two molecules of methionine convert to one molecule of cysteine, a critical precursor for glutathione (a major endogenous antioxidant) and essential for disulfide bond formation in structural proteins (like keratin in hooves).

安全性與警告

禁忌症

  • Renal failure
  • Pancreatic disease
  • Hepatic insufficiency
  • Preexisting acidosis
  • Oxalate or urate calculi
  • Kittens
  • Pre-existing metabolic acidosis
  • Severe liver disease or hepatic encephalopathy
  • Urate, cystine, or calcium oxalate urolithiasis
  • Young growing animals
  • Pregnant or nursing animals

不良反應

  • Gastrointestinal distress (nausea, vomiting)
  • Heinz-body hemolytic anemia (especially in cats)
  • Methemoglobinemia
  • Ataxia
  • Cyanosis
  • Metabolic acidosis
  • Gastrointestinal upset (nausea, vomiting, diarrhea)
  • Heinz body anemia (especially in cats at high doses)
  • Worsening of hepatic encephalopathy in patients with liver disease

注意事項

​Hepatic Warning:​ If used in patients with frank hepatic insufficiency, methionine can cause increased production of mercaptan-like compounds and intensify the signs of hepatic encephalopathy (dementia or coma).

  • ​Urolithiasis Risk:​ Do not give to animals with oxalate or urate calculi, as these stones thrive in acidic environments.
  • ​Dietary Overlap:​ Unmonitored use concurrently with an acidifying diet (e.g., s/d, c/d) may easily lead to severe metabolic acidosis and signs of overdose.
  • ​Age Restrictions:​ Strictly not recommended for use in kittens due to high susceptibility to toxicity.

藥物相互作用

Aminoglycosides (gentamicin, amikacin)

Urine acidification may diminish the effectiveness of aminoglycosides in treating bacterial urinary tract infections, as they are more effective in an alkaline medium.

Erythromycin

Urine acidification may diminish the effectiveness of erythromycin in treating bacterial urinary tract infections.

Quinidine

Urine acidification may increase the renal excretion of quinidine, potentially lowering its systemic levels.

Other urinary acidifiers (e.g., ammonium chloride)Major

Additive acidification leading to severe metabolic acidosis

Urinary acidifying dietsMajor

Excessive lowering of urine pH and increased risk of metabolic acidosis

監測

  • Urine pH (goal of therapy is typically ≤6.5)
  • Blood pH (if signs of toxicity or metabolic acidosis are present)
  • CBC in cats (if exhibiting signs of toxicity, to check for Heinz-body anemia)
  • Complete Blood Count (CBC) to monitor for Heinz bodies, especially in cats
  • Acid-base status (blood gases) if overdosage is suspected
  • Liver function

藥物動力學

半衰期

貓Not well documented狗Not well documented

吸收

Well absorbed from the gastrointestinal tract.

分佈

Widely distributed throughout the body tissues as it is an essential amino acid.

代謝

Metabolized in the liver to sulfate and urea.

排除

Excreted primarily by the kidneys into the urine.

過量

​Feline Toxicity:​ Cats are particularly sensitive to methionine overdose.

  • When administered at a dose of 2 grams orally per day to mature cats, it caused anorexia, methemoglobinemia, Heinz body formation (with resultant hemolytic anemia), ataxia, and cyanosis.
  • ​Kittens:​ Methionine may be highly toxic to kittens who consume other cats' food to which methionine has been added.

​General Toxicity:​ Metabolic acidosis can occur with overdoses in any species, particularly when used in combination with an acidifying diet. No specific information was located on the treatment of methionine overdosage; treatment should be symptomatic and supportive (e.g., correcting acid-base imbalances).

可用產品

劑型

  • Chewable tablets
  • Oral powder
  • Oral gel
  • Capsules
  • Topical ointment, cream, lotion, pads
  • Oral: 500 mg tablets

獸醫用

  • Methionine Tablets: 200 mg and 500 mg (Ammonil®, DL-Methionine Tablets®)
  • Methionine Chewable Tablets: 500 mg (Methio-Form®)
  • Methionine Powder (d-l-methionine Powder)
  • Methionine Gel: 400 mg (8%) per 120.5 gram tube (Methigel®)
  • 500 mg tablets (General Sale)

人用標示

  • Methionine Capsules: 500 mg
  • Topical Ointments, cream, lotion, pads and powder
  • Various OTC dietary supplements (typically 500 mg capsules/tablets)

各地核准狀態

European Union✓ 已核准EMA
🐕 Dogs🐈 Cats

Available as a general sale item.

United Kingdom✓ 已核准VMD
🐕 Dogs🐈 Cats

Classified as general sale.

暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

儲存與穩定性

Methionine should be stored at room temperature.

飼主須知

  • ​給藥方式：​ 請將此藥物與食物一起餵食或直接混入寵物的食物中，以減少腸胃不適並提高療效。

  • ​重要警告：​ 請勿給幼貓服用，並確保幼貓無法接觸到已添加此藥物的成貓食物。

  • ​飲食注意事項：​ 除非獸醫師特別指示，否則請勿將此藥物與處方泌尿道飲食（如 s/d 或 c/d）合併使用，因為這可能導致血液酸鹼值發生危險的變化。
  • ​何時應聯繫獸醫：​ 如果您的貓咪出現虛弱、食慾不振、走路不穩或牙齦蒼白/發紺等症狀，請立即聯繫您的獸醫師。

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