Esmolol

Brevibloc

Ultra-short-acting cardioselective β1 antagonist

Selective β1-adrenergic receptor antagonist. Decreases HR, contractility, conduction velocity, and AV node refractoriness. Selectivity for β1 over β2 reduces (does not eliminate) bronchospasm risk vs non-selective beta-blockers.

Indications

•Intraoperative tachycardia + hypertension (e.g., laryngoscopy, surgical stimulation, emergence)
•SVT rate control (a-fib, a-flutter, AVNRT)
•Aortic dissection (HR control before SBP control)
•Pheochromocytoma (after alpha blockade only)
•Thyroid storm

Dosing

Context	Adult	Pediatric
Loading bolus (intraop tachy/HTN)	0.5 mg/kg IV over 1 min (typical: 30–80 mg adult)	—
Maintenance infusion	50–300 mcg/kg/min IV titrated to HR/BP target	—
Pre-laryngoscopy blunting	0.5 mg/kg ~3 min before intubation, OR 1 mg/kg with second 0.5 mg/kg for severe HTN	—
Pediatric SVT		100–500 mcg/kg load over 1 min, then 50–200 mcg/kg/min infusion

Pharmacokinetics

Onset <1 min. Duration 9–10 min after stopping infusion. Metabolized by RBC ESTERASES (organ-independent — like remifentanil, but distinct esterase). Half-life ~9 min. Metabolite is inactive but excreted renally (caps duration in renal failure modestly).

Hemodynamic effects

↓HR (dominant), ↓contractility (modest), ↓BP. Reduces myocardial O₂ demand. Useful when avoiding tachycardia is critical (CAD, dissection, tight aortic stenosis).

Respiratory effects

Bronchospasm risk in asthma/COPD (less than non-selective; still present). Avoid in severe reactive airway disease.

Side effects

!Hypotension (additive with other antihypertensives, anesthetics)
!Bradycardia / AV block (especially with calcium channel blockers, digoxin)
!Bronchospasm in susceptible patients
!Heart block in patients with conduction system disease
!Acute decompensation in heart failure (negative inotrope)

Contraindications

×Severe sinus bradycardia, sick sinus syndrome
×2nd/3rd degree AV block (without pacemaker)
×Cardiogenic shock, decompensated heart failure
×Severe asthma (relative; selectivity not absolute)

Clinical pearls

★Best use case: intraop tachycardia in CAD patient — small bolus 30–50 mg shaves HR by 10–15 bpm without prolonged effect.
★DOSING CHECK: 100 mg in 10 mL (10 mg/mL); make calculation deliberate — never push 100 mg as a bolus (severe bradycardia/hypotension).
★Aortic dissection: esmolol is FIRST drug, even before SBP control with nicardipine (avoid reflex tachycardia from afterload reduction).
★Bridge to longer-acting: titrate esmolol intraop, transition to metoprolol/labetalol for postop period if continued β-blockade needed.
★Pheo: NEVER without adequate alpha blockade first (unopposed alpha → hypertensive crisis + lethal bradycardia).