Esmolol

Esmolol: Uses, Dosage and Side Effects

Overview

• An ultra-short-acting beta-blocker.
• It is relatively cardioselective and blocks beta-1 adrenergic receptors in the heart.
• It has a negative inotropic and chronotropic action which can lead to a decreased myocardial oxygen demand.
• It has an antiarrhythmic effect through its blockade of adrenergic stimulation of the heart.

Uses of Esmolol

• Therapy of, or as an assessment of the efficacy of beta-adrenergic blockers in the treatment of supraventricular tachycardias (including atrial fibrillation, atrial flutter and atrial tachycardia).
• Its effect is brief, persisting only 10–20 minutes after i.v. infusion.
• Other antiarrhythmic therapy must be used for chronic or maintenance therapy.

Dose of Esmolol in Dogs and Cats

Dogs, Cats:

• 0.05–0.5 mg/kg i.v. bolus over 5 min; 25–200 μg (micrograms)/kg/min constant rate infusion.

Side Effects of Esmolol in Dogs and Cats

• Including bradycardia, AV block, myocardial depression, heart failure, syncope, hypotension, hypoglycaemia, bronchospasm and diarrhoea.
• Depression and lethargy are occasionally seen and are a result of esmolol’s high lipid solubility and penetration into the CNS.
• Esmolol may reduce the glomerular filtration rate and therefore exacerbate any pre-existing renal impairment.

Contraindications of Esmolol in Dogs and Cats

• Patients with bradyarrhythmias, acute or decompensated congestive heart failure.
• Relatively contraindicated in animals with medically controlled congestive heart failure as it is poorly tolerated.
• Do not administer concurrently with alpha-adrenergic agonists.

Some Notes:

• The hypotensive effect of esmolol is enhanced by many agents that depress myocardial activity including anaesthetics, phenothiazines, antihypertensives, diuretics and diazepam.
• There is an increased risk of bradycardia, severe hypotension, heart failure and AV block if esmolol is used concurrently with calcium-channel blockers.
• Concurrent digoxin administration potentiates bradycardia.
• Esmolol may increase serum digoxin levels by up to 20%.
• Morphine may increase esmolol serum concentration by up to 50%.
• Esmolol may enhance the effects of muscle relaxants.
• The bronchodilatory effects of theophylline may be blocked by esmolol.