What is the equivalent dose of metoprolol tartrate for 150 mg of metoprolol succinate?

Metoprolol Succinate to Tartrate Conversion

The equivalent dose of metoprolol tartrate for 150 mg of metoprolol succinate is 150 mg of metoprolol tartrate, but this would need to be administered as 75 mg twice daily rather than once daily. 1

Pharmacokinetic Differences

Metoprolol comes in two salt forms with different release characteristics:

• Metoprolol Succinate (Extended-Release):

  • Once-daily dosing
  • Provides relatively constant plasma concentrations over 20-24 hours
  • Each pellet in the tablet acts as a diffusion cell releasing drug at a constant rate 1, 2
  • 95 mg of metoprolol succinate is equivalent to 100 mg of metoprolol tartrate in terms of beta-blocking activity 1

• Metoprolol Tartrate (Immediate-Release):

  • Typically dosed twice daily due to shorter half-life
  • Plasma concentrations fluctuate more throughout the day 2
  • Requires multiple daily doses to maintain therapeutic effect over 24 hours 3

Dosing Equivalence

The dosing equivalence between the two formulations is 1:1 in terms of total daily dose, but the administration schedule differs:

• 150 mg metoprolol succinate once daily = 150 mg metoprolol tartrate divided into two doses (75 mg twice daily)

This equivalence is supported by clinical guidelines that list metoprolol tartrate at 100-200 mg daily in divided doses and metoprolol succinate at 50-200 mg once daily 4.

Clinical Considerations

When converting between formulations, consider these important factors:

• Frequency of administration: Metoprolol tartrate requires twice-daily dosing for optimal effect 5, 3
• Adherence implications: Once-daily dosing with succinate may improve medication adherence
• Hemodynamic effects: Both formulations produce similar clinical effects when properly dosed 5
• Therapeutic context: For heart failure patients, metoprolol succinate CR/XL has been more extensively studied in large clinical trials 6

Practical Conversion Process

1. Maintain the same total daily dose (150 mg)
2. Divide the metoprolol tartrate dose into two equal administrations (75 mg twice daily)
3. Monitor for clinical response and adjust as needed

Common Pitfalls to Avoid

• Underdosing: Giving 150 mg metoprolol tartrate once daily would result in inadequate beta-blockade toward the end of the dosing interval due to its shorter half-life 3
• Overdosing: Giving the full 150 mg dose of metoprolol tartrate at once could lead to excessive beta-blockade initially with potential adverse effects
• Confusion between formulations: Always specify the salt form (succinate or tartrate) and release characteristics (extended-release or immediate-release) when prescribing 1, 6

This conversion maintains therapeutic equivalence while accounting for the different pharmacokinetic properties of the two metoprolol formulations.