美托洛爾
Metoprolol
Metoprolol tartrate, Metoprolol succinate
別名: Lopressor · Toprol XL · CGP-2175E · H-93/26
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 |
|---|---|---|---|---|---|
| For rate control in chronic atrial fibrillation | 0.25-1 mg/kg PO q1224h. | PO | q1224h | — | 🌎 NA |
| For CHF (early/mild or well-controlled) | 0.2 mg/kg PO twice daily, with slow titration upwards every 2-3 weeks up to 0.4-6.6 mg/kg PO three times a day. | PO | BID to TID | — | 🌎 NA |
| To decrease the incidence of atrial fibrillation and flutter in dogs undergoing valve surgery | 0.4-1 mg/kg PO q24h | PO | q24h | — | 🌎 NA |
- For rate control in chronic atrial fibrillation: Note: 'q1224h' is transcribed exactly as it appears in the source text, likely a typo for q12-24h.
- For CHF (early/mild or well-controlled): Many dogs will not tolerate this upward titration.
- To decrease the incidence of atrial fibrillation and flutter in dogs undergoing valve surgery: Using sustained release metoprolol (ToprolXR) administered before and as soon as feasible after surgery.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| As an oral beta blocker | 2-15 mg (total dose) PO q8h | PO | q8h | — | 🌎 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。
概覽
美托洛爾 (Metoprolol) 是一種心臟選擇性（β1-特異性）腎上腺素受體阻斷劑，廣泛應用於獸醫學中的多種心血管疾病管理。
主要臨床應用包括：
- 控制心室上性心搏過速及心室性期前收縮 (PVCs/VPCs)。
- 治療全身性高血壓。
- 治療貓的肥厚性心肌病 (HCM)，有助於減少動態左心室流出道阻塞並改善舒張期充盈時間。
由於其相對的 β1-選擇性，在患有併發支氣管收縮疾病（如貓氣喘）的病患中，美托洛爾通常被認為比非選擇性 β-阻斷劑（如普萘洛爾 propranolol）更安全，但在較高劑量下可能會失去選擇性，仍需謹慎使用。
作用機制
Metoprolol competitively blocks beta1-adrenergic receptors located primarily in the myocardium.
Mechanism Pathway: Blockade of beta1-receptors → decreased activation of adenylyl cyclase → reduced intracellular cAMP → decreased intracellular calcium influx.
This results in:
- Negative chronotropy: Decreased sinus heart rate.
- Negative dromotropy: Slowed atrioventricular (AV) conduction.
- Negative inotropy: Decreased myocardial contractility and cardiac output.
- Decreased myocardial oxygen demand and reduced blood pressure.
Clinical Pearl: Metoprolol lacks intrinsic sympathomimetic activity (ISA) and membrane-stabilizing activity. At higher dosages, its cardioselectivity diminishes, leading to beta2-receptor blockade in bronchial smooth muscle → potential bronchoconstriction.
安全性與警告
禁忌症
- Overt or unstable heart failure
- Hypersensitivity to beta-blockers
- Greater than first-degree heart block
- Sinus bradycardia
不良反應
- Bradycardia
- Lethargy and depression
- Impaired AV conduction
- Congestive heart failure (CHF) or worsening of heart failure
- Hypotension
- Hypoglycemia
- Bronchoconstriction (at high doses)
- Syncope
- Diarrhea
注意事項
Withdrawal Warning: Do not abruptly discontinue metoprolol therapy in chronic users. Abrupt cessation can lead to rebound tachycardia and exacerbation of clinical signs; taper the dose gradually.
- Respiratory Disease: Use with caution in patients with bronchospastic lung disease, even though it is relatively beta1-selective.
- Hepatic Impairment: Use cautiously in patients with significant hepatic insufficiency due to extensive hepatic metabolism.
- Endocrine: Can mask clinical signs of hypoglycemia and thyrotoxicosis. Use cautiously in labile diabetic patients as it can cause hypoglycemia or hyperglycemia.
- Cardiac: Use cautiously in patients with sinus node dysfunction or compensated CHF.
藥物相互作用
Increased risk for heart failure and hypotension due to additive myocardial depressant effects.
Concurrent use should be done with caution; additive negative inotropic and chronotropic effects, particularly in patients with preexisting cardiomyopathy or CHF.
May increase negative effects on SA or AV node conduction.
May increase the hypotensive effect of metoprolol.
May increase the risks for pulmonary hypertension in uremic patients.
May increase metoprolol plasma concentrations.
Potential for additive effects including hypotension and bradycardia.
May increase metoprolol plasma concentrations.
May have their actions blocked by metoprolol, and they may in turn reduce the efficacy of the beta-blocker.
監測
- Cardiac function
- Pulse rate
- ECG (if necessary)
- Blood pressure (if indicated)
- Signs of toxicity (bradycardia, hypotension, lethargy)
藥物動力學
半衰期
吸收
Rapidly and nearly completely absorbed from the GI tract, but undergoes a high first-pass effect (50%), reducing systemic bioavailability.
分佈
Very low protein binding (5-15%). Distributes well into most tissues. Crosses the blood-brain barrier (CSF levels are ~78% of serum levels). Crosses the placenta, and milk concentrations are 3-4 times higher than plasma.
代謝
Primarily biotransformed in the liver.
排除
Unchanged drug and metabolites are principally excreted in the urine.
過量
Overdosage primarily results in extensions of the drug's pharmacologic effects: hypotension, bradycardia, bronchospasm, cardiac failure, and potentially hypoglycemia.
Treatment:
- Decontamination: If recent oral ingestion, consider emptying the gut and administering activated charcoal. Caution: Inducing emesis can be risky as coma and seizures may develop rapidly.
- Monitoring: Continuous ECG, blood pressure, blood glucose, and potassium.
- Cardiovascular Support: Treat symptomatically. Use IV fluids and pressor agents for hypotension.
- Bradycardia: Treat with atropine. If atropine fails, isoproterenol may be given cautiously. A transvenous pacemaker may be necessary.
- Cardiac Failure: May be treated with digitalis glycosides, diuretics, and oxygen.
- Antidote: Glucagon (5-10 mg IV - human dose) may increase heart rate and blood pressure and reduce the cardiodepressant effects of metoprolol.
可用產品
劑型
- Oral tablets (tartrate)
- Extended-release oral tablets (succinate)
- Injection (tartrate)
- Compounded oral suspension
人用標示
- Metoprolol Tartrate Oral Tablets: 25 mg, 50 mg & 100 mg (Lopressor, generic)
- Metoprolol Succinate Extended-Release Tablets: 25 mg, 50 mg, 100 mg & 200 mg (Toprol XL, generic)
- Metoprolol Tartrate Injection: 1 mg/mL in 5 mL amps and Carpuject sterile cartridge units (Lopressor, generic)
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 all products protected from light. Store tablets in tight, light-resistant containers at room temperature. Avoid freezing the injection. Compounded oral suspensions (10 mg/mL) retain >95% potency for 60 days when stored at 4°C or 25°C and protected from light.
飼主須知
寵物主人重要須知
- 按時服藥是關鍵：為了達到療效，您的寵物必須完全按照獸醫的指示服用所有劑量。
- 切勿突然停藥：在未諮詢獸醫的情況下，絕對不要突然停止給藥，因為這可能會導致心跳危險地加快或使心臟病情惡化。
- 需要注意的症狀：如果您的寵物變得異常嗜睡、運動耐力下降、出現呼吸急促或咳嗽，或者行為和態度發生突然改變，請立即聯繫您的獸醫。
- 糖尿病寵物：如果您的寵物患有糖尿病，請密切監測其血糖，因為這種藥物可能會掩蓋低血糖的正常症狀。
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