Comparative Pharmacology
Head-to-head clinical analysis: LABETALOL versus TIMOLOL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LABETALOL versus TIMOLOL.
Labetalol vs TIMOLOL
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.
Nonselective beta-adrenergic receptor antagonist (beta-blocker) that competively blocks beta-1 and beta-2 receptors, reducing heart rate, contractility, and cardiac output. In glaucoma, decreases intraocular pressure by reducing aqueous humor production.
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.
0.25-0.5 mg ophthalmic solution instilled twice daily; for oral: 10-20 mg twice daily.
MODERATE Risk
MODERATE Risk
Clinical Note
moderateTimolol + Digoxin
"Timolol may increase the bradycardic activities of Digoxin."
Clinical Note
moderateTimolol + Digitoxin
"Timolol may increase the bradycardic activities of Digitoxin."
Clinical Note
moderateLabetalol + Digitoxin
"Labetalol may increase the bradycardic activities of Digitoxin."
Clinical Note
moderateTimolol + Deslanoside
"Timolol may increase the bradycardic activities of Deslanoside."
6-8 hours (terminal elimination half-life); may be prolonged in hepatic impairment, unchanged in renal impairment.
Terminal half-life: 4-5 hours (healthy adults); prolonged to 7-10 hours in renal impairment, 11-16 hours in hepatic impairment; clinical context: once-daily dosing for hypertension/glaucoma.
Renal (55-60% as unchanged drug and metabolites); biliary/fecal (minor, approximately 5-10%); remainder metabolized in liver.
Renal: ~20% unchanged; hepatic metabolism accounts for ~80%, with metabolites excreted renally; minor biliary/fecal elimination (<5%).
Category A/B
Category A/B
Alpha/Beta-Blocker
Beta-Blocker