Timolol Maleate (13 brand names, 4 dosage forms, 2 routes)
Available dosage forms: SOLUTION/DROPS, TABLET, SOLUTION, GEL FORMING/DROPS, SOLUTION.
Routes of administration: OPHTHALMIC, ORAL.
Brand Names
- BLOCADREN
- BRIMONIDINE TARTRATE AND TIMOLOL MALEATE
- BRIMONIDINE TARTRATE; TIMOLOL MALEATE
- COMBIGAN
- COSOPT
- COSOPT PF
- DORZOLAMIDE HYDROCHLORIDE AND TIMOLOL MALEATE
- ISTALOL
- TIMOLIDE 10-25
- TIMOLOL MALEATE
- TIMOPTIC
- TIMOPTIC IN OCUDOSE
- TIMOPTIC-XE
Indications and Usage
Dorzolamide hydrochloride and timolol maleate ophthalmic solution is indicated for the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension who are insufficiently responsive to beta-blockers (failed to achieve target IOP determined after multiple measurements over time). The IOP-lowering of dorzolamide hydrochloride and timolol maleate ophthalmic solution administered twice a day was slightly less than that seen with the concomitant administration of 0.5% timolol administered twice a day and 2% dorzolamide administered three times a day [see Clinical Studies (14)].
Dosage and Administration
The dose is one drop of dorzolamide hydrochloride and timolol maleate ophthalmic solution in the affected eye(s) two times daily. If more than one topical ophthalmic drug is being used, the drugs should be administered at least five minutes apart [see Drug Interactions (7.3)].
Mechanism of Action
Dorzolamide hydrochloride and timolol maleate ophthalmic solution is comprised of two components: Dorzolamide hydrochloride and timolol maleate. Each of these two components decreases elevated intraocular pressure, whether or not associated with glaucoma, by reducing aqueous humor secretion. Elevated intraocular pressure is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. The higher the level of intraocular pressure, the greater the likelihood of glaucomatous field loss and optic nerve damage. Dorzolamide hydrochloride is an inhibitor of human carbonic anhydrase II. Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport. Timolol maleate is a beta1 and beta2 (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. The combined effect of these two agents administered as dorzolamide hydrochloride and timolol maleate ophthalmic solution twice daily results in additional intraocular pressure reduction compared to either component administered alone, but the reduction is not as much as when dorzolamide administered three times daily and timolol twice daily are administered concomitantly. [See Clinical Studies (14)].
Overdosage
Symptoms consistent with systemic administration of beta-blockers or carbonic anhydrase inhibitors may occur, including electrolyte imbalance, development of an acidotic state, dizziness, headache, shortness of breath, bradycardia, bronchospasm, cardiac arrest and possible central nervous system effects. Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored. [See Adverse Reactions (6)]. A study of patients with renal failure showed that timolol did not dialyze readily.