Metoprolol vs Amlodipine
## Overview
Metoprolol (beta-1 selective beta-blocker) and amlodipine (dihydropyridine calcium channel blocker) are both first-line antihypertensives but with fundamentally different mechanisms. Amlodipine preferentially relaxes vascular smooth muscle (causing peripheral vasodilation); metoprolol reduces cardiac output and heart rate. In the ACCOMPLISH and ASCOT trials, amlodipine-based regimens demonstrated superior cardiovascular outcomes compared to atenolol (related to metoprolol) and HCTZ, elevating CCBs in hypertension guidelines.
## Mechanism of Action
Metoprolol: competitively blocks beta-1 adrenoceptors on the heart, reducing heart rate, AV conduction, and myocardial contractility. Blood pressure is lowered by reducing cardiac output. Also reduces sympathetic drive to the kidney (reduces renin release).
Amlodipine: blocks L-type voltage-gated calcium channels in vascular smooth muscle cells, preventing calcium entry required for vasoconstriction. Predominant peripheral vasodilation with minimal direct cardiac effect at therapeutic doses (dihydropyridine selectivity vs. phenylalkylamine CCBs like verapamil).
## Pharmacokinetics
Metoprolol IR: bioavailability ~50%, half-life 3–7 h, CYP2D6 metabolized. Metoprolol XL (succinate): once daily, 12–24 h duration. Amlodipine: oral bioavailability ~64–90%, very long half-life ~35–50 h, once daily, CYP3A4 metabolism.
## Clinical Evidence in Hypertension
ASCOT-BPLA: amlodipine + perindopril-based regimen significantly superior to atenolol + HCTZ for coronary events and stroke, establishing dihydropyridine CCB + RASI as preferred first-line combination. ACCOMPLISH: amlodipine + benazepril superior to HCTZ + benazepril in composite CV events. These trials positioned amlodipine as the preferred CCB.
Beta-blockers (including metoprolol) have been downgraded in hypertension guidelines (ESC/AHA) as preferred first-line agents (now listed as option 4 after CCBs, RAAS inhibitors, and thiazides) unless there is a compelling indication (HFrEF, AF rate control, angina, post-MI).
## Heart Failure
Metoprolol succinate XL: Class I evidence for HFrEF mortality reduction (MERIT-HF). Amlodipine: neutral in HF (PRAISE trial showed neutral mortality; it is safe in HF but does not reduce mortality). Amlodipine is acceptable for angina or hypertension management in HF patients but adds no mortality benefit.
## Angina
For angina pectoris: both are effective. Metoprolol reduces oxygen demand (decreases heart rate and contractility). Amlodipine reduces afterload and coronary vasospasm. Combination is often used.
## Key Takeaways
- Amlodipine: preferred antihypertensive (ASCOT/ACCOMPLISH superiority); edema side effect
- Metoprolol: necessary for HFrEF, AF rate control, angina, post-MI
- For uncomplicated hypertension without compelling indication, amlodipine preferred over metoprolol
Veredicto
Amlodipine is preferred for uncomplicated hypertension and vasospastic/stable angina based on superior cardiovascular outcomes data and convenient once-daily dosing. Metoprolol is preferred when there is a compelling cardiac indication — HFrEF (MERIT-HF mortality benefit), AF rate control, post-MI LV dysfunction, or stable angina requiring heart rate reduction. Combination therapy (amlodipine + metoprolol) is often used for angina with hypertension.