From the Guidelines
Metoprolol succinate is a beta-blocker medication that works by blocking the effects of adrenaline (epinephrine) on beta-1 receptors primarily found in the heart, thereby slowing the heart rate, reducing the force of heart contractions, and lowering blood pressure. This action is crucial in reducing the heart's workload and oxygen demand, making it an effective treatment for various cardiovascular conditions, including high blood pressure, angina, heart failure, and post-heart attack management 1. The succinate form of metoprolol is an extended-release version, providing steady medication levels throughout the day with once-daily dosing, which enhances patient compliance and reduces the risk of adverse effects.
Key Benefits and Mechanisms
- Slows the heart rate and reduces the force of heart contractions
- Lowers blood pressure and alleviates ischemia and angina
- Reduces the heart's workload and oxygen demand by preventing adrenaline from binding to beta-1 receptors
- Available in an extended-release form (succinate) for once-daily dosing
Clinical Evidence and Recommendations
The Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF) demonstrated a 34% reduction in mortality in patients with heart failure treated with metoprolol succinate compared to placebo 1. Similarly, the Carvedilol or Metoprolol European Trial (COMET) showed a 17% greater mortality reduction in favor of carvedilol compared to metoprolol tartrate, although the formulation used in MERIT-HF was metoprolol succinate 1. Based on these studies, metoprolol succinate is recommended for the long-term management of patients with hypertension-related left ventricular systolic dysfunction, along with other beta-blockers such as carvedilol, bisoprolol, and nebivolol.
Dosage and Administration
Typical dosages of metoprolol succinate range from 25 to 200 mg once daily, depending on the condition being treated and individual patient response. Patients should take it consistently at the same time each day, not crush or chew the tablets, and never stop taking it suddenly without medical supervision as this could worsen underlying conditions 1.
From the FDA Drug Label
Metoprolol is a beta 1-selective (cardioselective) adrenergic receptor blocker. This preferential effect is not absolute, however, and at higher plasma concentrations, metoprolol also inhibits beta 2-adrenoreceptors, chiefly located in the bronchial and vascular musculature Clinical pharmacology studies have demonstrated the beta-blocking activity of metoprolol, as shown by (1) reduction in heart rate and cardiac output at rest and upon exercise, (2) reduction of systolic blood pressure upon exercise, (3) inhibition of isoproterenol-induced tachycardia, and (4) reduction of reflex orthostatic tachycardia
Metoprolol succinate works by blocking beta 1-adrenergic receptors, which reduces the effects of catecholamines (such as adrenaline) on the heart, leading to:
- Decreased heart rate
- Decreased cardiac output
- Reduced systolic blood pressure It also has some effect on beta 2-adrenoreceptors at higher plasma concentrations. 2
From the Research
Mechanism of Action
- Metoprolol succinate is a beta-blocker that works by selectively blocking beta-1 adrenergic receptors in the heart, reducing heart rate and contractility 3, 4, 5.
- This mechanism of action leads to a decrease in myocardial oxygen demand, making it an effective treatment for conditions such as hypertension, angina pectoris, and heart failure 3, 6, 4.
Effects on Blood Pressure and Heart Rate
- Metoprolol succinate has been shown to lower blood pressure and heart rate in patients with hypertension, with greater reductions in diastolic blood pressure, heart rate, and rate-pressure product compared to other antihypertensive agents such as amlodipine 6.
- The extended-release formulation of metoprolol succinate provides consistent beta-1 blockade over a 24-hour period, allowing for once-daily dosing and improved patient compliance 4.
Clinical Applications
- Metoprolol succinate is indicated for the treatment of heart failure, where it has been shown to reduce mortality and morbidity by 34% compared to placebo 4, 7.
- It is also used in the treatment of atrial fibrillation, where it may reduce the incidence of new episodes in high-risk patients 7.
- Additionally, metoprolol succinate is used in the management of hypertension, particularly in patients with coronary heart disease, where it has been shown to reduce blood pressure and heart rate 3, 6.