Switching from Metoprolol Succinate 25mg Daily to Immediate-Release Metoprolol Tartrate
Do not switch from metoprolol succinate (extended-release) to metoprolol tartrate (immediate-release) for patients with heart failure, as only metoprolol succinate has proven mortality reduction in this population. 1
Critical Formulation Distinction
Only metoprolol succinate extended-release is proven to reduce mortality in heart failure by 34%, while metoprolol tartrate has not demonstrated this benefit and should not be used for heart failure management. 1, 2
- The MERIT-HF trial demonstrated that metoprolol succinate reduced all-cause mortality by 34%, cardiovascular mortality by 38%, sudden death by 41%, and death from progressive heart failure by 49% 1, 2
- The COMET trial found carvedilol superior to metoprolol tartrate, demonstrating that not all beta-blocker formulations are equivalent 1
- Only three beta-blockers have proven mortality reduction in heart failure: bisoprolol, carvedilol, and metoprolol succinate—this is not a class effect 3, 1
If Switching is Absolutely Necessary (Non-Heart Failure Indications Only)
Conversion Protocol for Hypertension or Angina
If the patient does not have heart failure and switching is required, convert metoprolol succinate 25mg once daily to metoprolol tartrate 25mg twice daily (50mg total daily dose). 4, 5
- Metoprolol tartrate requires twice-daily dosing due to its shorter half-life of 3-7 hours compared to the 24-hour release profile of metoprolol succinate 6, 7
- The immediate-release formulation produces higher peak plasma concentrations and more variable beta-blockade throughout the day 7
- For hypertension, metoprolol tartrate is dosed at 25-50mg twice daily initially, with a maximum of 200mg twice daily 4
Monitoring After Conversion
Monitor blood pressure and heart rate at 12 hours and 24 hours after the first dose of metoprolol tartrate to ensure adequate coverage throughout the dosing interval. 4, 8
- Blood pressure control may be less consistent with immediate-release formulation, particularly in the hours before the next dose 8, 7
- Heart rate should remain 50-60 bpm unless limiting side effects occur 4
- Watch for rebound hypertension or tachycardia in the late dosing interval (10-12 hours after dose) 8
Common Pitfalls to Avoid
Never abruptly discontinue metoprolol during the conversion process, as this can cause severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias with a 50% mortality rate in one study. 5, 4
- If the patient has coronary artery disease, the risk of rebound ischemia is particularly high during any beta-blocker transition 5
- Ensure no gap in beta-blockade coverage when switching formulations—give the first dose of tartrate at the time the next succinate dose would have been due 4
Do not assume equivalent dosing between formulations—metoprolol succinate 100mg contains 95mg of metoprolol succinate salt, which is considered equivalent to 100mg metoprolol tartrate in terms of metoprolol base content. 6
Special Considerations
For Patients with Heart Failure
If a patient with heart failure requires a switch due to cost or availability issues, strongly consider switching to bisoprolol or carvedilol rather than metoprolol tartrate, as these agents have proven mortality reduction. 1, 9
- Bisoprolol starting dose is 1.25mg once daily, titrated to target of 10mg daily 9
- Carvedilol starting dose is 3.125mg twice daily, titrated to target of 25-50mg twice daily 9
For Patients Requiring Divided Dosing
Consider administering metoprolol tartrate in smaller doses three times daily instead of larger doses twice daily to avoid higher peak plasma levels and maintain more consistent beta-blockade. 5