Comparative Pharmacology
Head-to-head clinical analysis: DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE versus INDERAL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE versus INDERAL.
DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE vs INDERAL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Dorzolamide is a carbonic anhydrase inhibitor that reduces aqueous humor secretion by inhibiting carbonic anhydrase in the ciliary processes. Timolol is a non-selective beta-adrenergic receptor antagonist that reduces aqueous humor production by blocking beta-2 adrenergic receptors in the ciliary epithelium.
Nonselective beta-adrenergic receptor antagonist; competes with catecholamines for binding at beta-1 and beta-2 receptors, decreasing heart rate, myocardial contractility, and blood pressure.
One drop of the fixed combination (dorzolamide 22.26 mg/mL, timolol 6.83 mg/mL) in the affected eye(s) every 12 hours.
Hypertension: 40 mg orally twice daily; increase as needed up to 640 mg/day. Angina: 80-320 mg orally daily in divided doses. Migraine prophylaxis: 80 mg orally daily in divided doses; up to 160-240 mg/day. Arrhythmias: 10-30 mg orally 3-4 times daily. IV: 1-3 mg IV bolus at 1 mg/min; may repeat after 2 min.
None Documented
None Documented
Dorzolamide: ~4 months but accumulates in RBCs; terminal half-life ~4-5 months due to binding to carbonic anhydrase. Timolol: ~4-6 hours.
3-6 hours (terminal). Clinical context: half-life increases with chronic dosing due to saturable hepatic metabolism; in cirrhosis, half-life may be prolonged to 10-23 hours.
Dorzolamide: primarily renal (approx. 80% unchanged), with minor biliary/fecal elimination. Timolol: renal (15-20% unchanged) and extensive hepatic metabolism with fecal excretion.
Renal: 96-99% as metabolites (active 4-hydroxypropranolol and conjugates), <1% unchanged. Biliary/fecal: minimal.
Category A/B
Category C
Beta-Blocker
Beta-Blocker