From the Guidelines
When converting from metoprolol tartrate 50 mg twice daily to carvedilol, start with carvedilol 6.25 mg twice daily, as recommended by the guidelines 1. This dose is considered a starting point for carvedilol, and it allows for titration to a maximum of 25 mg twice daily as tolerated. The conversion from metoprolol to carvedilol should be done with caution, as carvedilol has additional alpha-blocking properties that may cause more pronounced blood pressure lowering. Begin the first dose of carvedilol 24 hours after the last dose of metoprolol to avoid excessive beta-blockade. Carvedilol should be taken with food to reduce the risk of orthostatic hypotension. Some key points to consider during the conversion include:
- Monitoring blood pressure and heart rate closely during the transition
- Patients may experience increased fatigue, dizziness, or hypotension during the conversion
- After 1-2 weeks on the initial dose, if well tolerated and clinical response is inadequate, consider titrating up to carvedilol 25 mg twice daily
- The choice of beta blocker for an individual patient is based primarily on pharmacokinetic and side effect criteria, as well as on physician familiarity 1 The conversion is warranted because carvedilol offers additional benefits including alpha-blockade and antioxidant properties, which may provide superior outcomes in heart failure and post-myocardial infarction patients compared to selective beta-blockers like metoprolol. According to the guidelines, carvedilol can reduce mortality and reinfarction when given to patients with recent MI and LV dysfunction 1. It is also recommended to individualize the dose of carvedilol, starting with 6.25 mg twice daily and titrating to 25 mg twice daily as tolerated 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Conversion of Metoprolol Tartrate to Carvedilol
- The conversion of metoprolol tartrate 50 BID to carvedilol can be considered based on the equivalent beta-blocking effects of the two medications 2, 3.
- Studies have shown that carvedilol 25 mg BID has a similar effect on 24-h heart rate as metoprolol tartrate 50 mg BID 2.
- The Carvedilol Or Metoprolol European Trial (COMET) compared the effects of carvedilol and metoprolol on clinical outcomes in patients with chronic heart failure, with carvedilol showing a greater reduction in mortality than metoprolol tartrate 4.
- However, another study found that when metoprolol succinate was compared to carvedilol, there was no conclusive association between all-cause mortality and treatment with either medication after multivariable adjustment or propensity score matching 5.
Dosing Considerations
- The target dose of carvedilol in the COMET trial was 25 mg BID, while the target dose of metoprolol tartrate was 50 mg BID 4.
- Achieving the target beta-blocker dose was associated with a better outcome, and the superiority of carvedilol over metoprolol tartrate was maintained regardless of heart rate, blood pressure, or beta-blocker dose 6.
- The dose equivalents and pharmacological properties of the two medications should be considered when converting from metoprolol tartrate to carvedilol 3, 5.
Clinical Outcomes
- Carvedilol has been shown to have a greater reduction in mortality than metoprolol tartrate in patients with chronic heart failure 4.
- Both carvedilol and metoprolol have been shown to improve symptoms, quality of life, exercise capacity, and left ventricular ejection fraction in patients with chronic heart failure 3.
- The choice of beta-blocker should be individualized based on patient characteristics, comorbidities, and concomitant medications 5, 6.