Esmolol
Esmolol hydrochloride
Also known as: Brevibloc · Miniblock · ASL-8052 · Esmolol HCl · Esmololum · Esmolol hydrochloride
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| 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 | — | 🌎 NA |
| 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 | — | 🌎 NA |
| 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 | — | 🌎 NA |
| 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 | — | 🌎 NA |
- Ultra-short acting beta blockade (ventricular arrhythmias) - Normal cardiac function: If no loading dose, maximal effect should occur in 10-20 minutes.
- Ultra-short acting beta blockade - Severe dilated cardiomyopathy or severe mitral regurgitation: Do not give loading dose.
- Arrhythmia conversion: 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.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| 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 | — | 🌎 NA |
| 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 | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Esmolol is an ultra-short-acting, cardioselective beta-1 adrenergic receptor antagonist.
In veterinary medicine, it is primarily utilized as an intravenous infusion for the acute, short-term management of supraventricular tachyarrhythmias (SVTs) such as atrial fibrillation, atrial flutter, and sinus tachycardia. It is also highly valuable as a diagnostic test drug to determine if beta-blocker therapy will be effective and well-tolerated before transitioning a patient to a longer-acting oral beta-blocker. This is particularly useful in cats with hypertrophic cardiomyopathy (HCM) to assess if beta-blockade will reduce dynamic left-ventricular outflow tract obstruction.
Clinical Pearl: Because esmolol is rapidly metabolized by red blood cell esterases, its effects dissipate within 10-20 minutes after the infusion is stopped, making it exceptionally safe for trial therapy in critically ill patients.
Mechanism of action
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.
Safety & warnings
Contraindications
- Overt cardiac failure
- 2nd or 3rd degree AV block
- Sinus bradycardia
- Cardiogenic shock
- Second or third-degree AV block
- Uncompensated congestive heart failure
- Hypotension
Adverse effects
- Hypotension
- Bradycardia
- Heart block
- Exacerbation of congestive heart failure
- Bronchospasm (at high doses where beta-1 selectivity is lost)
Precautions
Use with caution (weigh benefit vs. risk) in patients with congestive heart failure (CHF), bronchoconstrictive lung disease, or diabetes mellitus. Esmolol may mask certain clinical signs of developing hypoglycemia (such as increased heart rate or blood pressure).
Drug interactions
Esmolol may increase serum digoxin levels up to 20%, but these drugs have been used together safely and effectively.
Concurrent use is not recommended due to potential risk of hypertension.
May increase steady-state esmolol serum concentrations up to 50%; titrate esmolol dosage carefully.
May see additive effects (hypotension, bradycardia) if used with esmolol.
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.
In humans, particularly with severe cardiomyopathy, cardiac arrest has occurred (rarely).
Additive negative inotropic and chronotropic effects; risk of severe bradycardia and hypotension
Increased risk of severe bradycardia
Mutual antagonism
Additive negative inotropic and chronotropic effects, increasing risk of severe bradycardia and hypotension.
Monitoring
- Continuous Electrocardiogram (ECG)
- Direct or indirect blood pressure
- Heart rate and rhythm
- Clinical signs of heart failure
Pharmacokinetics
Half-life
Absorption
Steady-state blood levels occur in about 5 minutes if a loading dose was given or about 30 minutes if no load was given.
Distribution
Rapidly and widely distributed but not appreciably to the CNS, spleen or testes. The distribution half-life is about 2 minutes. It is unknown whether the drug crosses the placenta or enters milk.
Metabolism
Rapidly metabolized in the blood by esterases to a practically inactive metabolite.
Elimination
Renal or hepatic dysfunction do not appreciably alter elimination characteristics.
Overdose
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.
Available products
Formulations
- Injection
- Injectable: 10 mg/ml solution
Human-labeled
- Esmolol HCl Injection: 10 mg/mL regular & preservative free in 10 mL vials
- Esmolol HCl Injection: 20 mg/mL preservative free in 5 mL vials & 100 mL bags
- Esmolol HCl Injection: 250 mg/mL in 10 mL ampules
- Brevibloc 10 mg/ml solution for injection
Regulatory status
POM (Prescription Only Medicine). Human-approved drug used under the cascade.
POM (Prescription Only Medicine). Human-approved drug used under the cascade.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
The concentrate for injection should be stored at room temperature; do not freeze and protect from excessive heat. After diluted to a concentration of 10 mg/mL esmolol HCl is stable (at refrigeration temperatures or room temperature) for at least 24 hours in commonly used IV solutions.
Client information
Esmolol is an emergency, ultra-short-acting medication administered exclusively in a veterinary hospital setting.
- Continuous Monitoring: Your pet will be closely monitored with an ECG (electrocardiogram) and blood pressure equipment while receiving this medication.
- Purpose: It is often used to rapidly stabilize dangerous heart rhythms or as a "test run" to see if your pet's heart condition will respond well to longer-acting oral beta-blockers.
- Safety: Because it clears from the bloodstream in minutes, any side effects (like low blood pressure or a slow heart rate) typically resolve very quickly once the infusion is stopped.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.