Beta-blocker · Antihypertensive · Rate control
Esmolol (Brevibloc)
Also called Brevibloc
Indications
- Rapid rate control of AF or flutter, perioperatively or in emergencies
- Noncompensatory sinus tachycardia
- Intraoperative and postoperative tachycardia and hypertension, including the intubation and emergence surge
- Aortic dissection, as anti-impulse therapy that stops fast if not tolerated (off-label)
- Thyroid storm with unstable hemodynamics (off-label)
- Dynamic LVOT obstruction, as in hypertrophic cardiomyopathy or SAM after mitral repair (off-label)
Dosing
Esmolol drip card and mL/h converterStart: Load 500 mcg/kg over 1 minute, then 50 mcg/kg/min
Mechanism of action
Esmolol is a competitive β1-selective adrenergic antagonist with no intrinsic sympathomimetic or membrane-stabilizing activity at therapeutic doses. Blocking β1 receptors in the SA node, AV node and myocardium keeps catecholamines from driving Gs, adenylyl cyclase and protein kinase A, so L-type calcium current and phase 4 depolarization fall; heart rate, AV conduction, contractility and oxygen demand drop. Red-cell esterases split the methyl ester on its side chain, so blockade fades 10–20 min after the infusion stops.
Pharmacology
- Cardiovascular: lowers heart rate, contractility, cardiac output and BP; slows AV conduction
- Cardiovascular: hypotension limits dosing (significant in 20–50% of trial patients, symptomatic in about 12%)
- Respiratory: β1 selectivity spares the bronchi at usual doses but fades as doses rise
- Metabolic: hides the tachycardia that warns of hypoglycemia; can raise serum potassium
- Renal: less renin release from juxtaglomerular β1 receptors
Pharmacokinetics
| Onset | Within minutes; steady state in 5 min with a load, 30 min without |
|---|---|
| Duration | Substantial recovery 10–20 min after stopping |
| Half-life | Distribution about 2 min; elimination about 9 min |
| Distribution | Vd 3.4 L/kg (UK SmPC) |
| Protein binding | 55%; acid metabolite 10% |
| Metabolism | Hydrolyzed by esterases in red-cell cytosol (not plasma cholinesterase) to an inactive acid and methanol, at levels well below toxic |
| Clearance | About 20 L/kg/h, more than cardiac output |
| Elimination | Under 2% unchanged in urine; the acid (half-life 3.7 h) is 73–88% of the dose |
| Organ failure | Liver disease: no change. ESRD: the nearly inactive acid's half-life rises about 12-fold to 48 h |
Chemistry
- Aryloxypropanolamine like propranolol plus a para-side-chain methyl ester: a soft drug designed for esterase breakdown
- Racemic, with one chiral carbon; β-blockade comes from the S-enantiomer
- pKa about 9.5 (secondary amine), so mostly ionized at pH 7.4; hydrophilic, with an octanol/water partition coefficient of 0.42 at pH 7 vs 17 for propranolol
- Ready-to-use 10 mg/mL vials and bags and 20 mg/mL bags in saline with acetate buffer, pH 4.5–5.5
Adverse effects and cautions
In the one-pagers
- Aortic Dissection and Hypertensive EmergencyAortic dissection: Beta-blocker FIRST (esmolol or labetalol), then a vasodilator (nicardipine, clevidipine or nitroprusside) if BP stays high
- Endocrine EmergenciesThyroid storm: 1. Beta-blocker: propranolol (also slows T4-to-T3), or esmolol if unstable
- Endocarditis and Valve EmergenciesValve emergencies: LVOT obstruction: SAM; worse on dobutamine; systolic murmur: Stop inotropes; fluid, esmolol, phenylephrine
- CEN Mental Health: Crisis, Suicide Risk, Eating Disorders and AbuseHyperventilation and caffeine: Caffeine (Willson 2018): a Red Bull can holds about 80 mg and a Monster about 160 mg, and one 473 mL product held 357 mg. Roughly 1 g may cause toxic symptoms, 2 g may need hospital care and 5 g or more is typically lethal; tachycardia is near universal above 10 mg/kg. Mild toxicity is irritability, palpitations, nausea, tremor and sweating; severe toxicity brings ve
- Rhythm GalleryAtrial rhythms: PACs, MAT, flutter and AF: Esmolol: 500 mcg/kg over 1 min, then 50–200 mcg/kg/min: Hypotension; wears off within 20 min
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Sources
- FDA label: Brevibloc (2025)
- UK SmPC: Brevibloc (2018)
- PubChem: esmolol
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.