エスモロール
エスモロールは、超短時間作用型で心臓選択性のある**ベータ1アドレナリン受容体拮抗薬**です。 獣医療では主に、心房細動、心房粗動、洞性頻脈などの上室性頻脈性不整脈（SVT）の急性かつ短期的な管理のための静脈内持続点滴として使用されます。また、より長時間作用する経口ベータ遮断薬に移行する前に、ベータ遮断薬療法が有効かつ忍容性があるかを判断するための**診断用テスト薬**としても非常に有用です。これは特に肥大型心筋症（HCM）の猫において、ベータ遮断が動的左室流出路狭窄を軽減するかどうかを評価するのに役立ちます。 > **臨床のポイント:** エスモロールは赤血球のエステラーゼによって急速に代謝されるため、点滴終了後10〜20分以内に効果が消失します。そのため、重症患者における試験的治療において極めて安全性が高い薬剤です。
作用機序: Esmolol competitively blocks **beta-1 adrenergic receptors** in the myocardium with minimal to no effect on beta-2 receptors at clinical doses. * **Negative Chronotropy:** Decreases heart rate by slowing sinoatrial (SA) node firing and increasing sinus cycle length. * **Negative Dromotropy:** Slows conduction velocity through the atrioventricular (AV) node and prolongs sinus node recovery time. * **Negative Inotropy:** Decreases myocardial contractility, which reduces myocardial oxygen demand. Unlike propranolol, esmolol lacks intrinsic sympathomimetic activity (ISA) and does not possess membrane-stabilizing (quinidine-like) or bronchoconstrictive effects.
動物種別の用量
- HCM (to determine if beta-blockers will reduce dynamic left-ventricular outflow tract obstruction) · An initial loading dose of 0.25-0.5 mg/kg (250-500 micrograms/kg) administered IV as slow bolus over 1-2 minutes, then followed by a constant rate infusion of 10-200 micrograms/kg/minute. · IV · CRI
- Critical Arrhythmias · Loading dose of 200-500 micrograms/kg IV over 1 minute; followed by a constant rate IV infusion of 25-200 micrograms/kg/minute · IV · CRI
- Ultra-short acting beta blockade (ventricular arrhythmias) - Normal cardiac function · An initial loading dose of 0.25-0.5 mg/kg (250-500 micrograms/kg) administered IV as slow bolus over 1-2 minutes, then followed by a constant rate infusion of 10-200 micrograms/kg/minute; or Start CRI at 10-200 micrograms/kg/minute without the bolus loading dose. · IV · CRI · If no loading dose, maximal effect should occur in 10-20 minutes.
- Ultra-short acting beta blockade - Severe dilated cardiomyopathy or severe mitral regurgitation · Start CRI at 10-20 micrograms/kg/min and titrate upward every 10 minutes to an effective endpoint. · IV · CRI · Do not give loading dose.
- SVTs · 0.05-0.1 mg/kg (50-100 micrograms/kg) IV bolus over 2 minutes; repeat every 5 minutes to a maximum of 0.5 mg/kg (500 micrograms/kg). · IV · q5m
- Arrhythmia conversion · Give in incremental IV bolus doses of 0.05-0.1 mg/kg every 5 minutes up to a maximum dose of 0.5 mg/kg. · IV · q5m · Because esmolol's effects are short-lived, if arrhythmia conversion does not occur, other negative inotropes (e.g., diltiazem, or verapamil) can be safely used 30 minutes after esmolol.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Overt cardiac failure
- 2nd or 3rd degree AV block
- Sinus bradycardia
- Cardiogenic shock
- Second or third-degree AV block
- Uncompensated congestive heart failure
- Hypotension
有害事象
- Hypotension
- Bradycardia
- Heart block
- Exacerbation of congestive heart failure
- Bronchospasm (at high doses where beta-1 selectivity is lost)
薬物相互作用
- Digoxin · Esmolol may increase serum digoxin levels up to 20%, but these drugs have been used together safely and effectively. · moderate
- Monoamine Oxidase Inhibitors (MAOIs) · Concurrent use is not recommended due to potential risk of hypertension.
- Morphine · May increase steady-state esmolol serum concentrations up to 50%; titrate esmolol dosage carefully.
- Reserpine · May see additive effects (hypotension, bradycardia) if used with esmolol.
- Vasoconstrictors/Inotropes (e.g., dopamine, epinephrine, norepinephrine) · If systemic vascular resistance is high, there is an increased risk for blocked cardiac contractility; esmolol is not recommended to control SVTs in patients receiving these drugs.
- Verapamil · In humans, particularly with severe cardiomyopathy, cardiac arrest has occurred (rarely). · major
- Calcium channel blockers (e.g., Diltiazem, Verapamil) · Additive negative inotropic and chronotropic effects; risk of severe bradycardia and hypotension · major
- Alpha-2 agonists (e.g., Dexmedetomidine) · Increased risk of severe bradycardia · major
- Sympathomimetics (e.g., Epinephrine) · Mutual antagonism · moderate
- Diltiazem · Additive negative inotropic and chronotropic effects, increasing risk of severe bradycardia and hypotension. · major
モニタリング
- Blood Pressure
- ECG
- Heart Rate
- Continuous Electrocardiogram (ECG)
- Direct or indirect blood pressure
- Heart rate and rhythm
- Clinical signs of heart failure
過量投与
The IV LD50 in dogs is approximately 32 mg/kg. * **2 mg/kg/min for 1 hour:** No adverse effects. * **3 mg/kg/min for 1 hour:** Produced ataxia and salivation. * **4 mg/kg/min for 1 hour:** Caused muscular rigidity, tremors, seizures, ptosis, vomiting, hyperpnea, vocalizations, and prostration. **Management:** These effects all resolved within 90 minutes of the end of infusion. Because of the short duration of action of the drug, discontinuation or dosage reduction may be all that is required; otherwise, symptomatic and supportive treatment may be initiated.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。