From the Guidelines
To convert from metoprolol tartrate 100 mg twice daily to carvedilol, I recommend starting carvedilol at 6.25 mg twice daily for 1-2 weeks, then increasing to 12.5 mg twice daily for 1-2 weeks, and finally to a target dose of 25 mg twice daily if tolerated. This recommendation is based on the most recent and highest quality study available, which suggests that carvedilol should be initiated at a dose of 6.25 mg twice daily and titrated up to a maximum of 25 mg twice daily 1.
Key Considerations
- Before starting this conversion, the patient should be clinically stable.
- Discontinue metoprolol tartrate when starting carvedilol; do not overlap these medications.
- Monitor blood pressure and heart rate closely during the transition, especially after the first dose of carvedilol which may cause hypotension.
- If the patient experiences significant hypotension, dizziness, or bradycardia, consider slowing the titration schedule.
Rationale
The conversion from metoprolol tartrate to carvedilol is necessary because carvedilol offers additional benefits over metoprolol, including alpha-blocking properties and greater antioxidant effects, which may provide better outcomes in heart failure and hypertension 1.
Administration
Carvedilol should be taken with food to reduce the risk of orthostatic hypotension, and patients should be advised to rise slowly from sitting or lying positions during the transition period.
Dosing
The dosing schedule for carvedilol is as follows:
- Start with 6.25 mg twice daily for 1-2 weeks
- Increase to 12.5 mg twice daily for 1-2 weeks
- Finally, increase to a target dose of 25 mg twice daily if tolerated This dosing schedule is based on the guidelines for the management of heart failure and hypertension, which recommend titrating carvedilol to a maximum of 25 mg twice daily 1.
From the Research
Equivalent Dosage of Carvedilol for Metoprolol Tartrate
To determine the equivalent dosage of Carvedilol for a patient taking Metoprolol tartrate 100 mg twice daily, we need to examine the available evidence.
- The COMET trial 2 compared the effects of carvedilol and metoprolol on clinical outcomes in patients with chronic heart failure. The target doses used in the trial were carvedilol 25 mg twice daily and metoprolol tartrate 50 mg twice daily.
- Another study 3 discussed the COMET trial and noted that the target doses used were debated, but the trial showed that drugs in the same class do not necessarily have the same effects.
- A review of beta-blockers for heart failure 4 mentioned that initiating dose should be very low and increased gradually over weeks, and treatment benefit appears proportional to magnitude of heart rate reduction.
- The SELECT trial 5 compared the beta-receptor selectivity of carvedilol and metoprolol succinate in patients with heart failure, but did not provide a direct comparison of dosages.
- The COMET trial results were also published in the American Heart Journal 6, which compared the effects of metoprolol tartrate and carvedilol on cause-specific mortality and morbidity in patients with chronic heart failure.
Dosage Comparison
Based on the available evidence, it appears that carvedilol 25 mg twice daily is equivalent to metoprolol tartrate 50 mg twice daily, as used in the COMET trial 2. However, the patient is currently taking metoprolol tartrate 100 mg twice daily, which is twice the dose used in the COMET trial.
- To determine the equivalent dosage of carvedilol, we can assume a proportional relationship between the dosages of metoprolol tartrate and carvedilol.
- Based on this assumption, the equivalent dosage of carvedilol for metoprolol tartrate 100 mg twice daily would be approximately 50 mg twice daily, as the COMET trial used carvedilol 25 mg twice daily for metoprolol tartrate 50 mg twice daily 2, 3, 6.