What is the maximum dosage of metoprolol (beta-blocker) for atrial fibrillation?

Maximum Dosage of Metoprolol for Atrial Fibrillation

The maximum oral dosage of metoprolol for atrial fibrillation is 100 mg twice daily for metoprolol tartrate or 400 mg once daily for metoprolol succinate (extended-release). 1

Metoprolol Formulations and Dosing

• Metoprolol tartrate (immediate-release):

  • Initial oral dose: 25-100 mg twice daily 1
  • Maximum oral dose: 100 mg twice daily 1
  • Intravenous dosing: 2.5-5 mg IV bolus over 2 minutes; up to 3 doses 1

• Metoprolol succinate (extended-release/XL):

  • Initial oral dose: 50 mg once daily 1
  • Maximum oral dose: 400 mg once daily 1
  • No intravenous formulation available 1

Rate Control Targets in Atrial Fibrillation

• Standard rate control strategy: Target resting heart rate <80 bpm for symptomatic management 2
• Lenient rate control strategy: Resting heart rate <110 bpm may be reasonable in asymptomatic patients with preserved left ventricular function 1, 2
• Adequacy of heart rate control should be assessed during physical activity as well as at rest 1

Titration and Administration

• Start with a low dose and gradually titrate upward based on heart rate response and patient tolerance 1, 2
• For acute management of rapid ventricular response, intravenous metoprolol can be administered at 2.5-5 mg IV bolus over 2 minutes, with up to 3 doses 1
• When transitioning from IV to oral therapy, oral metoprolol should be started at appropriate maintenance doses 1

Combination Therapy

• If rate control remains inadequate despite maximum tolerated dose of metoprolol, consider adding:
  • Non-dihydropyridine calcium channel blocker (diltiazem or verapamil) 2
  • Digoxin (particularly useful in patients with heart failure) 1
  • Amiodarone (when other measures are unsuccessful or contraindicated) 1

Cautions and Contraindications

• Avoid in patients with:

  • Decompensated heart failure 1, 2
  • Severe bradycardia or high-degree AV block without a pacemaker 2
  • Asthma or obstructive airway disease 1
  • Pre-excited atrial fibrillation 1

• Monitor for common adverse effects:

  • Hypotension 1, 2
  • Bradycardia 1, 2
  • Worsening heart failure 1, 2

Special Considerations

• In patients with heart failure and atrial fibrillation, metoprolol is generally well-tolerated when initiated at low doses and gradually increased 3
• Metoprolol may help prevent new-onset atrial fibrillation in patients with heart failure 4
• In patients with HFrEF and atrial fibrillation with rapid ventricular response, both metoprolol and diltiazem have shown similar efficacy for acute rate control 5
• Avoid abrupt discontinuation of metoprolol, which can lead to rebound tachycardia or exacerbation of ischemic heart disease 2

Alternative Beta-Blockers for Rate Control

If metoprolol is not tolerated or unavailable, other beta-blockers with established efficacy for rate control include:

• Atenolol: 25-100 mg once daily 1, 2
• Carvedilol: 3.125-25 mg twice daily 1, 2
• Bisoprolol: 2.5-10 mg once daily 1, 2
• Propranolol: 10-40 mg three to four times daily (total 80-240 mg daily) 1