What is the dosage for metoprolol (beta blocker) IV administration, either as a stat dose or infusion?

Metoprolol IV Dosing: Stat Bolus vs Infusion

For acute situations requiring IV metoprolol, administer 5 mg as a slow IV bolus over 1-2 minutes, which can be repeated every 5 minutes up to a maximum total dose of 15 mg (three 5 mg boluses). 1, 2 This is the standard stat dosing approach endorsed by both the American Heart Association and FDA labeling.

Stat Bolus Dosing Protocol

The preferred method is intermittent bolus administration rather than continuous infusion:

• Initial dose: 5 mg IV push over 1-2 minutes 1, 3, 2
• Repeat dosing: Additional 5 mg boluses every 5 minutes as needed 1, 3, 2
• Maximum total dose: 15 mg (three 5 mg boluses) 1, 3, 2
• Monitoring: Continuous blood pressure, heart rate, and ECG monitoring during administration 2

When to Use IV Metoprolol

Appropriate indications include:

• Stable narrow-complex tachycardias unresponsive to adenosine or vagal maneuvers 1
• Rate control in atrial fibrillation or atrial flutter 1
• Early treatment of acute myocardial infarction in hemodynamically stable patients 2, 4
• Certain polymorphic VT associated with acute ischemia 1

Critical Contraindications (Must Screen Before Administration)

Absolute contraindications - do NOT give IV metoprolol if ANY of these are present:

• Signs of heart failure or low output state 3, 2
• Systolic BP <120 mmHg 3
• Heart rate >110 bpm or <60 bpm 3
• PR interval >0.24 seconds 3
• Second or third-degree heart block 1, 3
• Active asthma or reactive airway disease 1, 3
• Decompensated heart failure 3
• Age >70 years with multiple risk factors (in acute MI setting) 3

Transition to Oral Therapy

After successful IV administration:

• Begin oral metoprolol 15 minutes after the last IV dose 3, 2
• Initial oral dose: 25-50 mg every 6 hours for 48 hours 3, 2
• Maintenance: 100 mg twice daily thereafter 2
• For patients who don't tolerate full IV dose: start with 25 mg orally every 6 hours 2

Continuous Infusion Alternative (Esmolol)

If continuous infusion is preferred over bolus dosing, use esmolol instead of metoprolol:

• Esmolol has a 2-9 minute half-life, allowing rapid titration 1
• Loading dose: 500 mcg/kg (0.5 mg/kg) over 1 minute 1
• Maintenance infusion: Start at 50 mcg/kg/min (0.05 mg/kg/min) 1
• Can increase to maximum 300 mcg/kg/min (0.3 mg/kg/min) 1
• Transition to oral metoprolol 25-50 mg the following morning 3

Common Pitfalls to Avoid

Critical safety considerations:

• Never give IV metoprolol to patients with pre-excited atrial fibrillation - may precipitate very rapid ventricular rates in WPW syndrome 1
• Have a defibrillator readily available when administering IV metoprolol 1
• Do not use in patients with decompensated heart failure - wait until clinical stabilization 3
• Avoid in acute MI patients with cardiogenic shock risk factors - increases shock risk by 11 per 1000 patients treated 3
• Monitor for hypotension and bradycardia - most common adverse effects requiring dose adjustment 1

Monitoring During IV Administration

Required monitoring parameters:

• Continuous ECG monitoring 2
• Blood pressure checks every 2-5 minutes during bolus administration 2
• Heart rate monitoring 2
• Auscultation for rales (heart failure) and bronchospasm 3
• Assessment for signs of low cardiac output 3