Propranolol Dose Equivalent to Metoprolol XR 100 mg
Metoprolol XR 100 mg daily is approximately equivalent to propranolol 160-200 mg daily, based on the established 1:2.5 dosing ratio between these beta-blockers. 1
Dosing Equivalence Calculation
The American College of Cardiology establishes that the conversion ratio between metoprolol and propranolol is approximately 1:2.5, meaning 100 mg of metoprolol equals roughly 250 mg of propranolol. 1 However, for metoprolol XR 100 mg once daily, the practical equivalent is:
- Propranolol immediate-release: 80-100 mg twice daily (160-200 mg total daily dose) 1
- Propranolol extended-release: 160-200 mg once daily 1
This accounts for the fact that metoprolol tartrate 50 mg twice daily (100 mg total) is approximately equivalent to propranolol 80-100 mg twice daily. 1
Formulation Considerations
Propranolol is available in two formulations that affect dosing frequency:
- Immediate-release: Requires 2-3 times daily dosing due to shorter half-life 1
- Extended-release: Allows once-daily dosing, more comparable to metoprolol XR 1
The extended-release propranolol formulation would be the most appropriate equivalent to metoprolol XR 100 mg, maintaining similar convenience of once-daily administration. 1
Important Pharmacologic Differences
Selectivity matters clinically:
- Metoprolol is beta-1 selective, making it potentially safer in patients with reactive airway disease, though caution remains warranted 1
- Propranolol is non-selective (blocks both beta-1 and beta-2 receptors) and should be avoided in patients with asthma or COPD 1
This selectivity difference means propranolol carries higher risk of bronchospasm and should not be used as a direct substitute in patients with any history of reactive airway disease. 1
Monitoring Parameters After Conversion
When switching between these medications, target the following:
- Resting heart rate: 50-60 beats per minute unless limiting side effects occur 1
- Blood pressure monitoring at each visit 1
- Watch for bronchospasm, particularly with propranolol in patients with any pulmonary history 1
- Signs of worsening heart failure during initiation 1
Common Pitfall to Avoid
Never abruptly discontinue either medication when switching—this can precipitate rebound hypertension or worsening angina. 1 When converting from metoprolol XR to propranolol, overlap the medications briefly or taper one while initiating the other to avoid withdrawal phenomena. 1