IV Metoprolol Dosing for Tachycardia
Administer metoprolol 5 mg IV as a slow bolus over 1-2 minutes, which can be repeated every 5 minutes as needed based on heart rate and blood pressure response, up to a maximum total dose of 15 mg. 1, 2, 3
Standard IV Administration Protocol
The FDA-approved dosing regimen consists of three separate 5 mg boluses given at approximately 2-minute intervals, with continuous monitoring between doses 3. The American Heart Association and American College of Cardiology support this protocol for supraventricular tachycardia, atrial fibrillation with rapid ventricular response, and other acute tachyarrhythmias requiring immediate rate control 1, 2.
Key administration details:
- Each 5 mg dose must be given slowly over 1-2 minutes, never as a rapid push 1, 2
- Wait 5 minutes between doses to assess hemodynamic response 1, 2, 3
- Maximum cumulative dose is 15 mg (three 5 mg boluses) 1, 2, 3
- Administer in a setting with intensive monitoring capabilities 3
Critical Contraindications to Verify Before Administration
Absolute contraindications that preclude any IV metoprolol use: 1, 2
- Signs of heart failure, low output state, or decompensated heart failure 1, 2
- Systolic blood pressure <100-120 mmHg with symptoms 1, 2
- Heart rate <60 bpm with symptoms OR paradoxically >110 bpm (increases cardiogenic shock risk) 1, 2
- Second or third-degree heart block or PR interval >0.24 seconds without a functioning pacemaker 1, 2
- Active asthma or reactive airways disease 1, 2
- Pre-excited atrial fibrillation (WPW syndrome) - metoprolol may paradoxically accelerate ventricular response 1
Required Monitoring During IV Administration
Continuous monitoring is mandatory throughout the administration period 1, 2, 3:
- Continuous ECG monitoring to detect bradycardia or heart block 1, 2
- Frequent blood pressure checks (every 2-5 minutes) to identify hypotension 1, 2, 3
- Auscultation for rales indicating pulmonary congestion 1
- Auscultation for bronchospasm, particularly in patients with any respiratory history 1, 2
- Assessment for symptomatic bradycardia (HR <60 bpm with dizziness or lightheadedness) 1
- Assessment for symptomatic hypotension (systolic BP <100 mmHg with dizziness, lightheadedness, or blurred vision) 1
Transition to Oral Therapy
After successful IV administration, transition to oral metoprolol 15 minutes after the last IV dose 1, 2:
- Initial oral dose: 25-50 mg every 6 hours for 48 hours 1, 2, 3
- Maintenance dosing: Transition to 100 mg twice daily after 48 hours 3
- For patients who did not tolerate the full 15 mg IV dose, start with 25 mg every 6 hours instead of 50 mg 3
Expected Clinical Response
In clinical studies, IV metoprolol achieved rate control in 69-81% of patients with supraventricular tachyarrhythmias 4, 5. The mean ventricular rate decreased from 134 to 106 beats/min within 10 minutes of administration, with maximum effect reached at 48 minutes 4. Rate control was maintained for 40-320 minutes without additional therapy 4.
Common Pitfalls to Avoid
Never administer the full 15 mg as a single rapid bolus - this significantly increases the risk of severe hypotension and bradycardia requiring intervention 1. Each 5 mg dose must be given slowly over 1-2 minutes with adequate time between doses to assess response 1, 2, 3.
Do not use in decompensated heart failure - wait until clinical stabilization occurs, as early IV metoprolol in high-risk patients increases cardiogenic shock risk by 11 per 1000 patients treated 1.
Hypotension is the most frequent adverse effect, occurring in approximately 31% of patients (5 of 16) in one study, though it was transient and readily managed 4. Have vasopressor support immediately available 1.
Alternative for High-Risk Patients
For patients at elevated risk of adverse effects, consider esmolol instead of metoprolol 1: