Comparative Pharmacology
Head-to-head clinical analysis: DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE versus INDERAL LA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE versus INDERAL LA.
DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE vs INDERAL LA
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.
Propranolol is a non-selective beta-adrenergic receptor antagonist that competitively blocks beta-1 and beta-2 receptors, decreasing heart rate, myocardial contractility, and blood pressure; also inhibits renin release and reduces sympathetic outflow.
One drop of the fixed combination (dorzolamide 22.26 mg/mL, timolol 6.83 mg/mL) in the affected eye(s) every 12 hours.
Initial: 80 mg orally once daily; titrate to 120-160 mg once daily; maximum 640 mg/day.
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.
Terminal elimination half-life is 8-11 hours (range 4-16 hours) after oral administration. The extended-release formulation (INDERAL LA) results in a prolonged half-life of approximately 10 hours, allowing once-daily dosing.
Dorzolamide: primarily renal (approx. 80% unchanged), with minor biliary/fecal elimination. Timolol: renal (15-20% unchanged) and extensive hepatic metabolism with fecal excretion.
Primarily hepatic metabolism with renal elimination of metabolites. Less than 1% excreted unchanged in urine. Biliary/fecal excretion of metabolites accounts for approximately 20% of eliminated dose.
Category A/B
Category C
Beta-Blocker
Beta-Blocker