From the Guidelines
Metoprolol and labetalol are distinct beta-blockers with different receptor selectivities and clinical uses, making metoprolol preferable for patients with respiratory conditions and labetalol more suitable for hypertensive emergencies and situations requiring rapid blood pressure control. The primary difference between metoprolol and labetalol lies in their receptor selectivity, with metoprolol being a selective beta-1 receptor blocker and labetalol blocking both beta and alpha receptors 1. This difference in selectivity affects their clinical applications, with metoprolol commonly used for hypertension, angina, heart failure, and after heart attacks at doses typically ranging from 25-100 mg twice daily, and labetalol being particularly valuable for hypertensive emergencies, pregnancy-related hypertension, and situations requiring rapid blood pressure control, with typical oral doses of 100-400 mg twice daily 1.
Key differences between the two drugs include:
- Receptor selectivity: Metoprolol is beta-1 selective, while labetalol is non-selective, blocking both beta and alpha receptors 1.
- Clinical applications: Metoprolol is preferred for patients with respiratory conditions like asthma or COPD, while labetalol is more suitable for hypertensive emergencies and situations requiring rapid blood pressure control 1.
- Dosage: Metoprolol is typically dosed at 25-100 mg twice daily, while labetalol is dosed at 100-400 mg twice daily for oral administration 1.
- Administration: Labetalol can be administered intravenously in emergencies, whereas metoprolol's intravenous use is more limited due to its selective action 1.
The choice between metoprolol and labetalol should be based on the individual patient's needs, considering factors such as the presence of respiratory conditions, the need for rapid blood pressure control, and the patient's overall clinical profile 1. In general, metoprolol is a safer choice for patients with respiratory conditions, while labetalol is preferred for hypertensive emergencies and situations requiring rapid blood pressure control.
From the FDA Drug Label
Metoprolol is a beta 1-selective (cardioselective) adrenergic receptor blocker. Labetalol HCl combines both selective, competitive, alpha1-adrenergic blocking and nonselective, competitive, beta-adrenergic blocking activity in a single substance.
The main difference between metoprolol and labetalol is:
- Beta selectivity: Metoprolol is a beta 1-selective blocker, while labetalol is a nonselective beta-blocker with both alpha1- and beta-adrenergic blocking activity.
- Mechanism of action: Metoprolol primarily works by blocking beta 1 receptors, reducing heart rate and cardiac output. Labetalol, on the other hand, combines alpha1- and beta-adrenergic blockade to lower blood pressure without significant reduction in heart rate.
- Clinical effects: Metoprolol is used to treat conditions like hypertension, angina pectoris, and myocardial infarction, while labetalol is used to treat hypertension, with its alpha1-blocking activity contributing to a decrease in blood pressure. 2 3
From the Research
Comparison of Metoprolol and Labetalol
- Metoprolol and labetalol are both used to treat hypertension, but they have different mechanisms of action and effects on the body 4, 5.
- Metoprolol is a beta1 selective adrenergic blocker, while labetalol is an alpha- and beta-adrenergic blocking agent 4.
- Both drugs have been shown to lower blood pressure and heart rate, but metoprolol has a greater effect on heart rate 4, 6.
- Labetalol has been found to lower sitting diastolic pressure more than metoprolol, and standing diastolic pressure more than both metoprolol and propranolol 6.
- The choice of beta-blocker is important, as benefit is not a class-effect, and some beta-blockers (such as labetalol and carvedilol) may have additional benefits due to their alpha-blocking activity or other mechanisms 7, 5.
Side Effects and Tolerability
- Both metoprolol and labetalol can cause side effects such as fatigue, dizziness, and nausea 4, 6.
- Metoprolol has been associated with bradycardia, while labetalol has been associated with dizziness and postural hypotension 4, 7.
- The lipophilicity of metoprolol may contribute to its side effects, such as insomnia and nightmares 7.
Clinical Use
- Labetalol may be preferred in certain situations, such as in the treatment of hypertension in the acute stage of myocardial infarction, due to its combined alpha- and beta-blocking activity 8.
- Metoprolol and other beta-blockers may still have an important role in the management of hypertension, particularly in certain compelling indications for cardiovascular disease 5.