Maximum Daily Dose of Lopressor (Metoprolol) IV
The maximum total dose of IV metoprolol (Lopressor) is 15 mg per day, administered as three separate 5 mg boluses given at 5-minute intervals. 1
Standard IV Dosing Protocol
- Initial dose: 2.5-5 mg IV bolus administered slowly over 1-2 minutes 2, 1
- Repeat dosing: Can be repeated every 5 minutes as needed based on hemodynamic response 2, 1
- Maximum total dose: 15 mg (three 5 mg boluses) 2, 1
This dosing regimen is consistent across multiple guidelines from the American College of Cardiology, American Heart Association, and Heart Rhythm Society for acute situations requiring IV metoprolol, including atrial fibrillation with rapid ventricular response, supraventricular tachycardia, and acute myocardial infarction. 2, 1
Critical Contraindications Before Administration
Do not administer IV metoprolol if any of the following are present:
- Signs of heart failure, low output state, or decompensated heart failure 2, 1
- Systolic blood pressure <120 mmHg 1
- Heart rate >110 bpm or <60 bpm 1
- PR interval >0.24 seconds 1
- Second or third-degree heart block 2, 1
- Active asthma or reactive airway disease 2, 1
- Evidence of cardiogenic shock risk (age >70 years, Killip class II-III) 1
Required Monitoring During Administration
Continuous monitoring must include: 1
- Heart rate monitoring
- Blood pressure checks (frequent)
- Continuous ECG monitoring
- Auscultation for new rales (pulmonary congestion)
- Auscultation for bronchospasm
Common Pitfalls to Avoid
- Never administer the full 15 mg as a single rapid bolus - this significantly increases the risk of hypotension and bradycardia 1
- Never use in decompensated heart failure - early IV metoprolol in acute MI patients increased risk of cardiogenic shock by 11 per 1000 patients, particularly in the first 24 hours 1
- Never use in pre-excited atrial fibrillation (WPW syndrome) - may paradoxically accelerate ventricular response 1
Transition to Oral Therapy
After IV administration, oral metoprolol tartrate (immediate-release) should be started 15 minutes after the last IV dose at 25-50 mg every 6 hours for 48 hours, rather than returning directly to extended-release formulation. 1
Alternative for High-Risk Patients
For patients at high risk of adverse effects, consider esmolol instead of IV metoprolol, with a loading dose of 500 mcg/kg over 1 minute and maintenance infusion starting at 50 mcg/kg/min, allowing for rapid titration and shorter duration of action. 1