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).