Intravenous Metoprolol Dosing for Heart Rate Control
For heart rate control in tachycardia, metoprolol tartrate should be administered intravenously at 5 mg over 1-2 minutes, repeated every 5 minutes as required, up to a maximum dose of 15 mg. 1
Dosing Protocol
- Initial dose: 5 mg IV over 1-2 minutes
- Repeat dosing: May repeat 5 mg IV every 5 minutes if needed
- Maximum total dose: 15 mg IV
- Monitoring: Continuous ECG, blood pressure, and heart rate monitoring during administration
Indications for IV Metoprolol
IV metoprolol is indicated for:
- Stable narrow-complex tachycardias unresponsive to adenosine or vagal maneuvers 1
- Control of ventricular rate in atrial fibrillation or atrial flutter 1
- Certain forms of polymorphic VT (associated with acute ischemia or catecholaminergic) 1
Administration Considerations
- Administer each bolus over 1-2 minutes to minimize risk of hypotension 1, 2
- During IV administration, continuously monitor blood pressure, heart rate, and ECG 2
- For patients who tolerate the full IV dose, oral metoprolol can be initiated 15 minutes after the last IV dose 2
Contraindications and Precautions
IV metoprolol should be avoided in patients with:
- Asthma or obstructive airway disease
- Decompensated heart failure
- AV block greater than first degree (without pacemaker)
- Cardiogenic shock
- Hypotension (systolic BP <90 mmHg)
- Severe bradycardia
- Pre-excited atrial fibrillation or flutter (Wolff-Parkinson-White syndrome) 1, 3
Special Populations
- Elderly patients: Use lower initial doses due to greater frequency of decreased hepatic, renal, or cardiac function 2
- Hepatic impairment: Lower doses are recommended due to likely increased blood levels 2
- Heart failure: Use with caution; monitor closely for worsening heart failure symptoms 1, 4
Clinical Efficacy
IV metoprolol has demonstrated effectiveness in:
- Reducing heart rate in supraventricular tachycardias 5
- Converting some patients with atrial flutter or fibrillation to sinus rhythm 5
- Managing multifocal atrial tachycardia, with reported conversion to sinus rhythm in many patients 6, 7
Common Pitfalls
- Inadequate monitoring: Always monitor vital signs and ECG during and after administration
- Too rapid administration: Administering boluses too quickly increases risk of hypotension and bradycardia
- Failure to recognize contraindications: Particularly important to avoid in patients with bronchospastic disease or decompensated heart failure
- Insufficient dose spacing: Allow adequate time between doses (5 minutes) to assess effect before administering subsequent doses
Remember that if a patient does not respond adequately to IV metoprolol, alternative agents such as diltiazem or esmolol may be considered based on the clinical scenario and patient characteristics.