What is the recommended dose conversion when switching from metoprolol tartrate to metoprolol succinate?

Metoprolol Tartrate to Succinate Conversion

When converting from metoprolol tartrate to metoprolol succinate, use a 1:1 dose conversion ratio, where 100 mg of metoprolol tartrate (given twice daily) equals 100 mg of metoprolol succinate (given once daily). 1

Dosage Equivalence

• Metoprolol tartrate is typically administered twice daily (BID), while metoprolol succinate (XL/ER) is administered once daily (QD) 1
• A 100 mg metoprolol succinate extended-release tablet contains 95 mg of metoprolol succinate and is considered therapeutically equivalent to 100 mg of metoprolol tartrate 2
• Common dosing ranges:
  • Metoprolol tartrate: 25-100 mg BID (total daily dose 50-200 mg) 1
  • Metoprolol succinate: 50-400 mg QD 1

Pharmacological Differences

• Metoprolol succinate uses a controlled release/extended-release formulation 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
• Both formulations produce similar hemodynamic and clinical effects despite different dosing schedules 3

Clinical Considerations for Conversion

• When transitioning from tartrate to succinate in patients with cardiovascular conditions:

  • For patients on metoprolol tartrate 25 mg BID → convert to metoprolol succinate 50 mg QD 1
  • For patients on metoprolol tartrate 50 mg BID → convert to metoprolol succinate 100 mg QD 1
  • For patients on metoprolol tartrate 100 mg BID → convert to metoprolol succinate 200 mg QD 1

• In post-MI or heart failure patients, a gradual transition over 2-3 days from metoprolol tartrate to succinate is recommended to ensure stable blood levels 1

Special Considerations

• Metoprolol succinate may offer advantages over tartrate in certain clinical scenarios:

  • Better adherence with once-daily dosing 2
  • More consistent 24-hour beta-blockade with fewer peak/trough fluctuations 2, 3
  • May be preferred in heart failure patients due to more consistent hemodynamic effects 3

• Common pitfalls to avoid:

  • Ensure patients understand the change in dosing frequency (from twice daily to once daily) to prevent medication errors 1
  • Monitor for adequate blood pressure and heart rate control during the transition period 1
  • Be aware that metoprolol succinate is sometimes available in higher single doses than tartrate (up to 400 mg) 1