Equivalent Dose of Metoprolol Succinate to Metoprolol Tartrate 50 mg BID
The equivalent dose of metoprolol succinate to metoprolol tartrate 50 mg twice daily (BID) is 100 mg once daily (QD). 1
Pharmacological Equivalence
Metoprolol is available in two salt forms with different dosing schedules:
- Metoprolol tartrate: Immediate-release formulation administered twice daily 1
- Metoprolol succinate: Extended-release formulation administered once daily 1
The dosing equivalence between these formulations is established in clinical guidelines:
- 100 mg metoprolol succinate (extended-release) once daily = 100 mg metoprolol tartrate total daily dose (50 mg twice daily) 1, 2
- This equivalence is based on the pharmacokinetic properties of both formulations 2
Pharmacokinetic Considerations
- Metoprolol succinate is designed to provide relatively constant plasma concentrations over approximately 20 hours 2
- After ingestion, the metoprolol succinate tablet disintegrates into individual pellets with each pellet acting as a diffusion cell releasing the drug at a relatively constant rate 2
- A 100 mg metoprolol succinate tablet contains 95 mg of metoprolol succinate and is considered to have equivalent activity to 100 mg metoprolol tartrate 2
Clinical Evidence Supporting Equivalence
- In heart failure patients, 100 mg once daily metoprolol succinate produced similar hemodynamic effects to 50 mg twice daily metoprolol tartrate 3
- Both formulations demonstrated comparable beta-blocking effects at the end of the dosing interval 4
- The total effect over the dose interval, expressed as the area under the efficacy curve (AUEC), was similar for both formulations despite differences in plasma concentrations 4
Practical Dosing Considerations
When switching between formulations:
- Metoprolol tartrate 25-50 mg BID (total daily dose 50-100 mg) = Metoprolol succinate 50-100 mg QD 1
- Metoprolol tartrate 50 mg BID (total daily dose 100 mg) = Metoprolol succinate 100 mg QD 1
Clinical Advantages of Extended-Release Formulation
- More consistent 24-hour blood pressure control, particularly in the early morning hours 5
- Improved medication adherence with once-daily dosing 2
- Less fluctuation in plasma drug levels, potentially reducing peak-related side effects 4
Common Pitfalls and Caveats
- Avoid confusion between salt forms: Always specify whether prescribing metoprolol tartrate or metoprolol succinate 1
- Do not crush or split extended-release formulations: This would destroy the controlled-release mechanism 2
- Consider timing of administration: Metoprolol succinate should be administered once daily, while metoprolol tartrate requires twice-daily dosing for equivalent effect 1
- Be aware of different brand names: Metoprolol tartrate (Lopressor) vs. metoprolol succinate (Toprol-XL) can cause confusion 1
Remember that despite the different dosing schedules, both formulations provide equivalent beta-blockade when dosed appropriately, with the succinate form offering the convenience of once-daily administration.