When to Switch from Metoprolol Tartrate to Metoprolol Succinate
Switch from metoprolol tartrate to metoprolol succinate when treating patients with heart failure with reduced ejection fraction (HFrEF), as metoprolol succinate is the evidence-based formulation proven to reduce mortality in this population.
Clinical Context and Evidence Base
The distinction between metoprolol formulations is critical for patient outcomes, particularly in heart failure management:
Heart Failure with Reduced Ejection Fraction (HFrEF)
Metoprolol succinate (extended-release) is the preferred formulation for HFrEF because it was the specific formulation studied in landmark mortality trials 1.
Bisoprolol and metoprolol succinate are specifically identified as preferred agents in patients with HFrEF, while metoprolol tartrate lacks this designation 1.
The NICE guideline explicitly notes that metoprolol succinate has similar effects on heart failure mortality as carvedilol and bisoprolol, whereas metoprolol tartrate showed inferior outcomes 1.
The COMET trial demonstrated that carvedilol reduced mortality compared to metoprolol tartrate, which the guideline authors attributed to the short-acting nature of the tartrate formulation used 1.
Key Switching Scenarios
Immediate switch indicated when:
A patient develops heart failure with reduced ejection fraction while already on metoprolol tartrate for another indication (hypertension, post-MI, atrial fibrillation rate control) 1.
The patient has newly diagnosed HFrEF and requires beta-blocker initiation—start with metoprolol succinate rather than tartrate 1.
The patient is being optimized on guideline-directed medical therapy for HFrEF and is currently on metoprolol tartrate 1.
Dosing Conversion
When switching formulations:
Metoprolol tartrate 100-200 mg twice daily converts to metoprolol succinate 50-200 mg once daily 1.
The once-daily dosing of succinate improves adherence while maintaining therapeutic effect 1.
Hemodynamic studies show equivalent acute and chronic effects between formulations despite the fourfold greater starting dose typically used with succinate 2.
Other Clinical Situations
For hypertension management:
- Either formulation is acceptable, though succinate offers once-daily convenience 1.
- Metoprolol tartrate 100-200 mg twice daily or metoprolol succinate 50-200 mg once daily are both listed as appropriate options 1.
For atrial fibrillation rate control:
- Both formulations are acceptable for acute and chronic rate control 1.
- Metoprolol tartrate 2.5-5 mg IV for acute control, then 25-100 mg twice daily orally, or metoprolol succinate 50-400 mg once daily for maintenance 1.
For post-STEMI patients:
- Either formulation can be used, with the guideline specifically mentioning transition from metoprolol tartrate to succinate over 2-3 days 1.
- Target dose of 200 mg daily as tolerated, which can be achieved with either formulation 1.
Critical Caveats
Do not assume bioequivalence means therapeutic equivalence—the FDA approval process for generic formulations allows substantial variability in achieved serum levels 3.
Avoid abrupt cessation of either formulation to prevent rebound hypertension and cardiac events 1.
The evidence base for beta-blockers in heart failure is established only for bisoprolol, metoprolol succinate, carvedilol, and nebivolol—not metoprolol tartrate 1.
When switching formulations in any patient, monitor heart rate, blood pressure, and clinical status after the change 1.