Differences Between Metoprolol Succinate and Metoprolol Tartrate
Metoprolol succinate (extended-release) is preferred over metoprolol tartrate (immediate-release) for most cardiovascular conditions due to its once-daily dosing, consistent 24-hour beta-blockade, and proven mortality benefits in heart failure. 1
Formulation Differences
Metoprolol Succinate
- Extended-release formulation that releases medication gradually over approximately 20 hours 2, 3
- Provides consistent plasma concentrations throughout 24 hours without significant peaks and troughs 3
- 100 mg of metoprolol succinate is equivalent to 100 mg of metoprolol tartrate in beta-blocking activity 4
- After ingestion, the tablet disintegrates into individual pellets with each acting as a diffusion cell releasing the drug at a relatively constant rate 4
Metoprolol Tartrate
- Immediate-release formulation with more pronounced peaks and troughs in plasma concentration 3
- Shorter half-life requiring multiple daily dosing 5
- More fluctuations in beta-blockade throughout the day 3
Dosing Differences
| Parameter | Metoprolol Succinate | Metoprolol Tartrate |
|---|---|---|
| Frequency | Once daily | Twice daily (or more) |
| Hypertension Dosing | 50-400 mg once daily [1] | 25-100 mg twice daily [1] |
| Heart Failure Dosing | Start at 12.5-25 mg once daily, target 200 mg once daily [1] | Start at 6.25-12.5 mg twice daily, target 50 mg twice daily [6] |
| Angina Dosing | 100-400 mg once daily | 50-100 mg twice daily |
Efficacy Differences
Heart Failure
- Metoprolol succinate has demonstrated mortality benefits in large clinical trials (MERIT-HF) with a 34% reduction in all-cause mortality 2
- Metoprolol succinate is one of only three beta-blockers (along with bisoprolol and carvedilol) proven to reduce mortality in heart failure 1
- The COMET trial showed that carvedilol had better mortality outcomes compared to immediate-release metoprolol tartrate, but this has not been compared with metoprolol succinate 1
Hypertension and Angina
- Both formulations are effective for blood pressure control and angina symptom relief 5
- The consistent 24-hour beta-blockade with succinate may provide more stable blood pressure control 4
Clinical Advantages of Metoprolol Succinate
- Improved adherence: Once-daily dosing improves patient compliance 2
- Consistent beta-blockade: More even plasma concentrations provide consistent beta-1 blockade throughout 24 hours 3
- Fewer peak-related side effects: Less pronounced peak concentrations may reduce side effects 3
- Better nocturnal coverage: Extended coverage may provide better protection during early morning hours when cardiovascular events are more common 4
Clinical Considerations and Pitfalls
- Initiation in heart failure: Both formulations should be started at low doses and gradually uptitrated to target doses to avoid hemodynamic compromise 1, 7
- Switching between formulations: When switching from tartrate to succinate, maintain equivalent total daily dose (e.g., 50 mg twice daily tartrate = 100 mg once daily succinate) 4
- Abrupt discontinuation: Never abruptly discontinue either formulation as this may precipitate angina, myocardial infarction, or arrhythmias 7
- Common error: Prescribing metoprolol tartrate at once-daily dosing, which provides inadequate 24-hour coverage 5
- Cost considerations: Metoprolol tartrate is generally less expensive but requires twice-daily dosing
Specific Clinical Scenarios
- Heart failure: Metoprolol succinate is strongly preferred due to proven mortality benefits 1
- Post-MI: Either formulation is effective, but succinate may provide more consistent protection 1
- Hypertension: Either formulation is effective; succinate offers convenience of once-daily dosing 1
- Patients with adherence concerns: Metoprolol succinate is preferred due to once-daily dosing 2
Tapering When Discontinuing
- Gradual tapering is essential for both formulations
- Reduce dose by half every week for 3 weeks 7
- Monitor for rebound symptoms including angina, tachycardia, and hypertension 7
Both formulations are selective beta-1 blockers with similar efficacy when used at appropriate doses and intervals, but metoprolol succinate offers significant advantages in dosing convenience and consistent beta-blockade, making it the preferred option for most cardiovascular indications, especially heart failure.