Timolol

What it is and how it works

Mechanism of Action Timolol maleate is a beta 1 and beta 2 (non-selective) adrenergic receptor inhibitor that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. Timolol GFS, when applied topically to the eye, has the action of reducing elevated, as well as normal, intraocular pressure, whether or not accompanied by glaucoma. Elevated intraocular pressure is a major risk factor in the pathogenesis of glaucomatous visual field loss and optic nerve damage. The precise mechanism of the ocular hypotensive action of Timolol GFS is not clearly established at this time.

Indications

Timolol GFS 0.25% and 0.5% are indicated for the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma. Timolol GFS is a beta adrenergic blocker indicated for the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma .

Dosage and administration (summary)

Instill one drop of Timolol GFS (either 0.25% or 0.5%) in the affected eye(s) once daily. Shake once before each use. Timolol GFS may be used alone or in combination with other intraocular pressure lowering medications. Concomitant topical ophthalmic medications should be administered at least 10 minutes before instilling Timolol GFS. Instill one drop in the affected eye(s) once daily .

Contraindications

Timolol GFS is contraindicated in patients with: • bronchial asthma • history of bronchial asthma • severe chronic obstructive pulmonary disease • sinus bradycardia • second or third degree atrioventricular block • overt cardiac failure • cardiogenic shock • hypersensitivity to any component of this product.

Warnings and precautions

• Same adverse reactions found with systemic administration of beta-adrenergic receptor inhibitors may occur with topical ophthalmic administration . • Beta-adrenergic receptor inhibitors may mask signs and symptoms of hypoglycemia and should be administered with caution in diabetic patients subject to hypoglycemia . • Beta-adrenergic receptor inhibitors may mask certain clinical signs (e.g. tachycardia) of hyperthyroidism . Systemic Absorption As with many topically applied ophthalmic drugs, Timolol GFS is absorbed systemically.

Pregnancy

Pregnancy Risk Summary There are no adequate and well-controlled studies in pregnant women with timolol maleate to inform a drug-associated risk. Administration of oral timolol maleate to pregnant mice, rats and rabbits did not produce teratogenicity at clinically relevant systemic exposures (see Data).

Storage and supply

Timolol GFS (timolol maleate ophthalmic gel forming solution) 0.25% and 0.5%, are both supplied as either a 2.5 mL or 5 mL slightly opalescent, colorless to nearly colorless solution in a 5 mL white polyethylene bottle with a natural polyethylene dropper tip and a yellow polypropylene overcap.

Source: Timolol Maleate (Timolol Gfs) — US FDA prescribing information, 2024-05-28, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.