Timolol Maleate
Indications
Timolol Maleate Ophthalmic Solution is indicated in the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.
Pharmacology
Timolol is a non-selective β-adrenergic receptor blocker. It does not have significant intrinsic sympathomimetic activity, direct myocardial depressant activity or local anaesth activity. Exact mechanism of ocular hypotensive effect is unclear, but it is thought to be related to reduction of aqueous humour formation. β-blockade also causes lowering of BP.
Dosage And Administration
Eye drops Solution: Initially, instill 1 drop of 0.25% solution bid into the affected eye(s), may increase to 1 drop of 0.5% solution bid if there is inadequate response; decrease to 1 drop once daily if controlled. Do not exceed 1 drop bid of 0.5% solution.
Gel-forming eye drops: 0.25% or 0.5% Gel-forming eye drops: Instill 1 drop into the affected eye(s) once daily.
Interaction
Although Timolol used alone has little or no effect on pupil size, mydriasis resulting from concomitant therapy with Timolol Maleate and epinephrine has been reported occasionally. Drug interactions of Timolol Maleate have been noticed with concomitant administration of beta-adrenergic blocking agents (both oral and topical), calcium antagonists, catecholamine-depleting drugs, digitalis, quinidin, clonidine, injectable epinephrine.
Contraindications
Timolol is contraindicated in patients with bronchial asthma, a 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.
Side Effects
Burning and stinging sensation of the eyes, bradycardia, hypotension, arrhythmia and AV or SA nodal block, CHF, pulmonary oedema, Raynaud's phenomenon, headache, dizziness, fatigue, asthenia, abdominal discomfort, nausea, constipation, hypoglycaemia.
Pregnancy And Lactation
Pregnancy: There are no adequate and well-controlled studies in pregnant women. Timolol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Lactation: Timolol has been detected in breast milk following oral and ophthalmic drug administration. Because of the potential for serious adverse reactions from Timolol in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Precautions And Warnings
Patients with inadequate cardiac function, DM, myasthenia gravis, cerebrovascular insufficiency, history of atopy. Avoid abrupt withdrawal as it may exacerbate angina symptoms or precipitate MI in patients with coronary artery disease, or precipitate thyroid crisis in patients with thyrotoxicosis. Patients undergoing major surgery. May mask signs of hyperthyroidism and hypoglycaemia. Ophth soln should not be used as monotherapy for angle-closure glaucoma. Renal and hepatic impairment. Pregnancy and lactation.
Overdose Effects
There have been reports of inadvertent overdosage with Timolol Ophthalmic Solution resulting in systemic effects similar to those seen with systemic beta-adrenergic blocking agents such as dizziness, headache, shortness of breath, bradycardia, bronchospasm, and cardiac arrest.
Therapeutic Class
Drugs for miotics and glaucoma.
Storage Conditions
Store between 15-30° C. Avoid freezing and protect from light.