What is the difference between propranolol and metoprolol (beta-blockers) in the treatment of hypertension and angina?

From the Guidelines

Propranolol and metoprolol are both effective beta-blockers for treating hypertension and angina, but metoprolol is generally preferred due to its cardioselectivity, which reduces respiratory side effects in patients with asthma or COPD. The key differences between propranolol and metoprolol lie in their selectivity and clinical applications. Propranolol is a non-selective beta-blocker that blocks both beta-1 (heart) and beta-2 (lungs, blood vessels) receptors, while metoprolol is a cardioselective beta-blocker that primarily targets beta-1 receptors 1. For hypertension, metoprolol is typically preferred at doses of 25-100 mg twice daily or 50-200 mg once daily for extended-release formulations, as its selectivity reduces respiratory side effects in patients with asthma or COPD. Some key points to consider when choosing between propranolol and metoprolol include:

• Metoprolol's cardioselectivity makes it safer for patients with respiratory conditions, though this selectivity diminishes at higher doses 1.
• Propranolol has additional uses for migraine prevention, essential tremor, and anxiety symptoms due to its ability to cross the blood-brain barrier more readily 1.
• Both medications can cause fatigue, bradycardia, and hypotension, and neither should be abruptly discontinued as this can trigger rebound hypertension or angina 1.
• For patients with diabetes, metoprolol's selectivity may offer advantages by causing less masking of hypoglycemia symptoms compared to propranolol 1. According to the most recent guidelines, metoprolol is recommended as a first-line treatment for hypertension and angina, due to its efficacy and safety profile 1.

From the FDA Drug Label

In controlled, comparative, clinical studies, metoprolol has been shown to be as effective an antihypertensive agent as propranolol, methyldopa, and thiazide-type diuretics, to be equally effective in supine and standing positions A controlled, comparative, clinical trial showed that metoprolol was indistinguishable from propranolol in the treatment of angina pectoris.

The main difference between propranolol and metoprolol is their selectivity:

• Propranolol is a non-selective beta-blocker, blocking both beta-1 and beta-2 adrenergic receptors.
• Metoprolol is a selective beta-1 blocker, primarily blocking beta-1 adrenergic receptors.

In terms of efficacy, both drugs have been shown to be effective in the treatment of:

• Hypertension: Both metoprolol and propranolol have been shown to be effective in reducing blood pressure.
• Angina pectoris: Both drugs have been shown to be effective in reducing the frequency of angina attacks and improving exercise tolerance.

Key differences:

• Metabolism: Metoprolol is primarily metabolized by CYP2D6, while propranolol is extensively metabolized by the liver through multiple pathways.
• Half-life: The half-life of metoprolol is 3-4 hours, while the half-life of propranolol is 3-6 hours.

Overall, both propranolol and metoprolol are effective beta-blockers used to treat hypertension and angina, but they have some differences in terms of selectivity, metabolism, and half-life 2, 3.

From the Research

Comparison of Propranolol and Metoprolol

• Both propranolol and metoprolol are beta-blockers used in the treatment of hypertension and angina pectoris 4.
• Metoprolol is a beta1-selective adrenoceptor blocking drug, which means it has a more targeted effect on the heart compared to propranolol, a non-selective beta-blocker 5.
• Studies have shown that metoprolol is as effective as propranolol in reducing angina attacks and improving exercise tolerance in patients with uncomplicated angina pectoris 4.
• Metoprolol has been found to be well tolerated and its beta1-selectivity may facilitate its administration to certain patients, such as asthmatics and diabetics, in whom non-selective beta-blockers are contraindicated 6.

Therapeutic Efficacy

• Metoprolol has been shown to be effective in reducing mortality and improving clinical status in patients with stable mild to moderate chronic heart failure due to left ventricular systolic dysfunction 7.
• Propranolol has been found to be effective in reducing angina frequency and improving exercise tolerance, but its use in patients with certain conditions, such as asthma, may be limited due to its non-selective beta-blocking effects 4.
• The combination of metoprolol with other drugs, such as diuretics, has been found to be effective in the treatment of hypertension 8.

Pharmacokinetic and Pharmacodynamic Properties

• Metoprolol has a longer duration of effect than expected from its half-life, making it suitable for twice daily administration, and its controlled-release/extended-release formulation allows for once daily administration 6, 8.
• Propranolol has a shorter duration of effect and requires more frequent administration compared to metoprolol 4.
• The pharmacokinetic and pharmacodynamic properties of metoprolol make it a useful option for patients with hypertension and angina pectoris, particularly those who require a more targeted and convenient treatment regimen 6, 8.