Which beta blocker, carvedilol or metoprolol, has the least effect on blood pressure?

From the Guidelines

Metoprolol generally has less effect on blood pressure compared to carvedilol. Metoprolol is a selective beta-1 blocker, primarily affecting the heart, while carvedilol is a non-selective beta blocker that also has alpha-blocking properties. This means carvedilol has a more pronounced effect on lowering blood pressure due to its additional vasodilating action 1. When prescribing for conditions where minimal blood pressure reduction is desired, metoprolol would be the preferred choice between these two. Typical starting doses are metoprolol 25-50 mg twice daily or carvedilol 3.125-6.25 mg twice daily, titrated as needed. The selective nature of metoprolol means it's less likely to cause side effects related to blocking beta-2 receptors in the lungs and blood vessels. This makes metoprolol a better option for patients with respiratory issues or those who are more sensitive to blood pressure changes. However, the choice between these medications should always be based on the specific patient's condition, comorbidities, and treatment goals. In some cases, carvedilol's broader action may be beneficial, especially in heart failure patients where its additional effects can improve outcomes, as seen in the Carvedilol or Metoprolol European Trial (COMET) which demonstrated a 17% greater mortality reduction in favor of carvedilol compared with metoprolol tartrate 1. It's also worth noting that the National Institute for Health and Clinical Excellence guideline recommends considering beta-blockers, including metoprolol and carvedilol, for all patients with left ventricular systolic dysfunction, and introducing them in a “start-low, go-slow” manner to avoid adverse effects 2. Key points to consider when choosing between metoprolol and carvedilol include:

• The patient's specific condition and comorbidities
• The desired level of blood pressure reduction
• The patient's sensitivity to beta-blocker side effects
• The potential benefits of carvedilol's additional alpha-blocking properties in certain patients.

From the Research

Comparison of Carvedilol and Metoprolol

• Carvedilol and metoprolol are both beta blockers, but they have different effects on blood pressure due to their distinct pharmacological properties 3, 4, 5.
• Carvedilol is a non-selective beta blocker with additional alpha-blocking effects, which can lead to vasodilation and a decrease in blood pressure 3, 6, 5.
• Metoprolol, on the other hand, is a beta(1)-selective beta blocker, which primarily affects the heart rate and contractility 3.

Effects on Blood Pressure

• Studies have shown that carvedilol tends to have a lesser effect on blood pressure compared to metoprolol, particularly at rest 3, 5.
• Carvedilol has been found to reduce blood pressure by decreasing vascular resistance, whereas metoprolol reduces blood pressure mainly by decreasing cardiac output 6, 5.
• One study found that carvedilol had a smaller effect on systolic blood pressure (-4 mmHg) compared to metoprolol (-10 mmHg) 7.

Clinical Implications

• The differences in blood pressure effects between carvedilol and metoprolol may be relevant in clinical practice, particularly in patients with hypertension or heart failure 4, 6.
• Carvedilol may be a better option for patients who require a beta blocker with minimal effects on blood pressure, such as those with orthostatic hypotension or vasospastic disorders 6, 5.
• However, more research is needed to fully understand the clinical implications of these differences and to determine the optimal beta blocker for individual patients 3, 7.