What is the recommended intravenous esmolol loading dose and infusion rate to achieve rate control in an adult patient with tachycardia, assuming no contraindications such as severe bradycardia, high‑grade atrioventricular block, hypotension, decompensated heart failure, severe asthma, or β‑blocker allergy?

Esmolol Infusion for Heart Rate Control

For acute rate control in adult tachycardia, administer esmolol as a 500 mcg/kg loading dose over 1 minute, followed immediately by a continuous infusion starting at 50 mcg/kg/min, titrating upward by 50 mcg/kg/min increments every 4–5 minutes to a maximum of 200 mcg/kg/min until target heart rate is achieved. 1, 2, 3

Standard Dosing Protocol

Loading dose:

• Administer 500 mcg/kg IV over 1 minute as the initial bolus 1, 2, 3
• A higher loading dose of 1000 mcg/kg may be used in urgent situations, though 500 mcg/kg is standard 2
• The loading dose may be repeated before each dose escalation if additional rapid control is needed 2

Maintenance infusion:

• Begin at 50 mcg/kg/min immediately after the loading dose 1, 2, 3
• Titrate upward in 50 mcg/kg/min increments every 4–5 minutes based on heart rate response 1, 2, 3
• Maximum dose: 200 mcg/kg/min for tachycardia (300 mcg/kg/min for hypertension, though doses above 200 mcg/kg/min provide minimal additional heart rate reduction and increase adverse effects) 1, 2, 3
• Maintenance infusions may be continued for up to 48 hours 3

Pharmacokinetic Advantages

Esmolol's ultra-short half-life of 9 minutes (range 4–16 minutes) makes it uniquely suited for situations requiring rapid titration and immediate reversibility 2, 4, 5, 6

• Onset of action: 2 minutes, with 90% of steady-state beta-blockade occurring within 5 minutes 5, 6
• Full recovery from beta-blockade: 18–30 minutes after terminating the infusion 5
• Esmolol blood concentrations become undetectable 20–30 minutes post-infusion 5
• Without a loading dose, continuous infusion reaches steady-state in approximately 30 minutes 3

Absolute Contraindications

Do not administer esmolol in patients with: 2

• Second- or third-degree heart block without a functioning pacemaker
• Bradycardia (heart rate <60 bpm)
• Decompensated heart failure with signs of low cardiac output or cardiogenic shock
• Active asthma or severe reactive airway disease
• Pre-excited atrial fibrillation (Wolff-Parkinson-White syndrome), as beta-blockade may paradoxically accelerate ventricular response

Required Monitoring During Infusion

Continuous monitoring is mandatory throughout esmolol administration: 2

• Continuous cardiac monitoring with ECG to detect conduction abnormalities
• Heart rate monitoring to assess for excessive bradycardia
• Blood pressure monitoring to detect hypotension (the most common adverse effect, occurring in 12–50% of patients) 5, 7
• Clinical assessment after each dose change: auscultate for pulmonary rales (heart failure) and bronchospasm 2

Specific Clinical Scenarios

Supraventricular tachycardia:

• Use the standard loading dose (500 mcg/kg over 1 minute) followed by 50 mcg/kg/min maintenance, titrating every 4–5 minutes until ventricular rate control is achieved 2
• Therapeutic response is defined as ≥20% reduction in heart rate, heart rate <100 bpm, or conversion to normal sinus rhythm 7
• The average dose producing therapeutic response is approximately 97.5 mcg/kg/min 7

Perioperative tachycardia (immediate control):

• Administer 1 mg/kg as a bolus over 30 seconds followed by an infusion of 150 mcg/kg/min if necessary 3
• Adjust the infusion rate as required to maintain desired heart rate and blood pressure 3

Perioperative tachycardia (gradual control):

• Administer 500 mcg/kg bolus over 1 minute followed by 50 mcg/kg/min for 4 minutes, then titrate as outlined above 3

Acute aortic dissection:

• Esmolol is a preferred agent for rapid reduction of systolic blood pressure to ≤120 mmHg, with beta-blockade preceding vasodilator administration to prevent reflex tachycardia 2

Common Pitfalls and Management

Hypotension is the most frequently reported adverse effect: 2, 5, 7

• Incidence increases at doses >150 mcg/kg/min and in patients with low baseline blood pressure 5
• Hypotension typically resolves within 30 minutes after discontinuing or reducing the infusion 5, 7
• Down-titrate or discontinue the infusion if symptomatic hypotension occurs; complete disappearance of clinical effects occurs in 20–30 minutes 4

Doses above 200 mcg/kg/min:

• Provide little additional heart rate reduction 1, 3
• May block beta-2 receptors, potentially affecting lung function in patients with reactive airway disease 2
• Increase the rate of adverse reactions 3

Drug incompatibilities:

• Esmolol is not compatible with sodium bicarbonate (5%) solution or furosemide (causes precipitation) 2, 3
• Never mix esmolol with these agents in the same IV line 2

Transition to Oral Beta-Blocker

When transitioning from esmolol to an oral beta-blocker: 2

1. Administer the first dose of the alternative oral agent
2. 30 minutes later, reduce the esmolol infusion rate by 50%
3. After the second dose of the alternative agent, monitor the patient's response
4. If satisfactory control is maintained for 1 hour, discontinue the esmolol infusion