What is the equivalent dosage of metoprolol tartrate (50 mg twice daily) when converted to carvedilol (generic name for Coreg)?

From the Guidelines

When switching from metoprolol tartrate 50 mg twice daily to carvedilol, start with carvedilol 6.25 mg twice daily, uptitrated individually at 3- to 10-d intervals to a maximum of 25 mg twice daily, as recommended by the guidelines 1. This approach allows for a gradual transition, minimizing the risk of rebound effects and enabling close monitoring of the patient's response to the new medication. The selection of carvedilol is based on its pharmacokinetic and side effect profile, as well as the clinician's familiarity with the agent 1. It is essential to monitor blood pressure and heart rate closely, especially during the initial titration period, and to adjust the dose accordingly to avoid adverse effects such as dizziness, fatigue, and hypotension 1. Carvedilol's unique mechanism of action, which includes blocking both beta-1 and beta-2 receptors plus alpha-1 receptors, provides additional vasodilation effects that may benefit patients with heart failure or hypertension 1. The target resting heart rate is 50 to 60 beats per minute unless a limiting side effect is reached, and the maintenance dose should be individualized based on the patient's response to the medication 1. It is crucial to note that the transition should be gradual, and patients should be closely monitored for any signs of worsening heart failure, symptomatic hypotension, or excessive bradycardia 1. In patients with marked first-degree AV block, any form of second- or third-degree AV block, or a history of asthma, severe LV dysfunction, or HF, beta blockers should be used with caution or avoided altogether 1. The guidelines recommend that beta blockers be initiated orally, in the absence of contraindications, within the first 24 hours, and that the choice of beta blocker be based on pharmacokinetic and side effect criteria, as well as physician familiarity 1. Overall, the switch from metoprolol tartrate to carvedilol should be done under close supervision, with careful monitoring of the patient's response to the new medication, and with consideration of the patient's individual characteristics and medical history 1. Key points to consider during the switch include:

• Starting with a low dose of carvedilol (6.25 mg twice daily) and uptitrating as needed and tolerated
• Monitoring blood pressure and heart rate closely, especially during the initial titration period
• Adjusting the dose based on the patient's response to the medication
• Being aware of the potential for adverse effects such as dizziness, fatigue, and hypotension
• Considering the patient's individual characteristics and medical history when selecting a beta blocker and determining the optimal dose.

From the Research

Comparison of Metoprolol Tartrate and Carvedilol

• Metoprolol tartrate 50 mg twice daily and carvedilol 25 mg twice daily have similar effects on 24-h heart rate in patients with chronic heart failure 2.
• The degree of beta1-blockade produced by these two drugs in these doses is comparable, and the superior survival effect of carvedilol compared to metoprolol seen in COMET is likely to be due to actions of carvedilol other than beta1-blockade 2.
• In outpatients with chronic heart failure, no conclusive association between all-cause mortality and treatment with carvedilol or metoprolol succinate was observed after either multivariable adjustment or multilevel propensity score matching 3.

Efficacy of Carvedilol and Metoprolol in Chronic Heart Failure

• Bisoprolol, carvedilol, and metoprolol succinate have similar effects on mortality amongst patients with chronic heart failure 4.
• Carvedilol and metoprolol tartrate produced highly significant improvement in symptoms, exercise capacity, and LV ejection fraction, with no significant differences between the two drugs 5.
• Carvedilol had a significantly greater effect on sitting and standing blood pressure, LV end-diastolic dimension, and normalized the mitral E wave deceleration time compared to metoprolol 5.

Clinical Trials and Studies

• The Carvedilol or Metoprolol European Trial (COMET) compared carvedilol with short-acting metoprolol tartrate at different dose equivalents 2, 3.
• The PASSAT Study compared carvedilol and metoprolol in patients with acute myocardial infarction undergoing primary coronary intervention, and found no significant differences in myocardial injury and improvement of global and regional LV function 6.
• A randomized double-blind control trial compared the long-term clinical efficacy of treatment with metoprolol versus carvedilol in patients with chronic heart failure, and found both drugs to be equally effective in improving symptoms, quality of life, exercise capacity, and LV ejection fraction 5.