Comparative Pharmacology
Head-to-head clinical analysis: LABETALOL versus METOPROLOL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LABETALOL versus METOPROLOL.
Labetalol vs Metoprolol
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Labetalol is a racemic mixture of four stereoisomers, each with distinct activity. It is a non-selective beta-adrenergic antagonist (blocking beta1 and beta2 receptors) and a selective alpha1-adrenergic antagonist. The alpha1 blockade causes vasodilation and reduces peripheral vascular resistance, while beta blockade reduces heart rate and myocardial contractility, leading to decreased blood pressure without significant reflex tachycardia.
Selective beta-1 adrenergic receptor antagonist; competitively blocks beta-1 receptors in the heart, decreasing heart rate, contractility, and cardiac output; reduces renin release from kidneys.
Oral: 200-1200 mg/day in 2 divided doses; initial 100 mg twice daily. IV: 20 mg bolus over 2 minutes, may repeat 40 mg at 10-minute intervals. Max cumulative dose: 300 mg.
Metoprolol tartrate: Initial 50 mg PO BID or 100 mg PO daily; maintenance 100-450 mg/day in divided doses. Metoprolol succinate (extended-release): Initial 25-100 mg PO once daily; maintenance 100-400 mg once daily.
MODERATE Risk
MODERATE Risk
Clinical Note
moderateMetoprolol + Digoxin
"Metoprolol may increase the bradycardic activities of Digoxin."
Clinical Note
moderateMetoprolol + Digitoxin
"Metoprolol may increase the bradycardic activities of Digitoxin."
Clinical Note
moderateLabetalol + Digitoxin
"Labetalol may increase the bradycardic activities of Digitoxin."
Clinical Note
moderateMetoprolol + Deslanoside
"Metoprolol may increase the bradycardic activities of Deslanoside."
6-8 hours (terminal elimination half-life); may be prolonged in hepatic impairment, unchanged in renal impairment.
3–7 hours for metoprolol; prolonged in poor CYP2D6 metabolizers (up to 8–16 hours). Clinical context: dosing interval typically twice daily (immediate-release) or once daily (extended-release).
Renal (55-60% as unchanged drug and metabolites); biliary/fecal (minor, approximately 5-10%); remainder metabolized in liver.
Primarily hepatic metabolism (CYP2D6) producing inactive metabolites; renal excretion accounts for <5% unchanged. Fecal elimination minimal.
Category A/B
Category C
Alpha/Beta-Blocker
Beta-Blocker