Timolet 0.5% Eye Drop

Side Effects of Timolet 0.5% Eye Drop

Fatigue, headache, coldness of extremities, paraesthesia, GI symptoms, dyspnoea, skin rash, alopecia, dry mouth, bradycardia. Ophthalmic use: Burning, stinging, blurred vision, ocular irritation (e.g. conjunctivitis, blepharitis, crusting), decreased corneal sensitivity, visual disturbances, diplopia, ptosis, cystoid macular oedema, pseudopemphigoid, choroidal detachment following filtration surgery. Adverse reactions associated with systemic administration of β-blocker may occur with ophthalmic use. Potentially Fatal: Heart failure, intensification of heart block, bronchospasm, respiratory failure.

Drug Interactions

Hypotensive action may be reduced by NSAIDs. Increased hypotensive effect of other antihypertensives, general anaesthetics, catecholamine-depleting drugs e.g. reserpine. Use with methoxyflurane may cause cardiac depression. Decreased response to sympathomimetics. Increased β-blockade activity with CYP2D6 inhibitors e.g. quinidine. Increased risk of AV prolongation with diltiazem, verapamil and digoxin. May exacerbate rebound hypertension following abrupt discontinuance of clonidine in patients receiving a concomitant beta-blocker. Potential additive effects of β-blockade in patients receiving both oral and ophthalmic β-blockers. Concomitant use of 2 ophthalmic β-blockers is not recommended.

Contraindications

Present or history of bronchial asthma, severe COPD, sinus bradycardia, 2nd and 3rd degree heart block, sick sinus syndrome, overt heart failure, cardiogenic shock, severe peripheral vascular disease/Raynaud's disease), Prinzmetal angina, untreated pheochromocytoma, metabolic acidosis, hypotension.

Mechanism of Action

Timolol is a non-selective β-adrenergic receptor blocker. It does not have significant intrinsic sympathomimetic activity, direct myocardial depressant activity or local anaesthetic activity. Exact mechanism of ocular hypotensive effect is unclear, but it is thought to be related to reduction of aqueous humor formation. Beta-blockade also causes lowering of blood pressure. Onset: Ophthalmic: About 30 min. Absorption: Oral: Rapid and almost completely absorbed (about 90%); plasma concentration peaks in 1-2 hr. Ophthalmic: Part of the dose is absorbed systemically. Distribution: Not extensively protein-bound. Crosses the placenta and distributed into breast milk. Metabolism: Undergo first-pass metabolism and partially metabolised in the liver. Plasma half-life: 4hr. Excretion: Excreted in urine as metabolites and unchanged drug.

Special Precautions

Due to systemic absorption of ophthalmic preparations, adverse reactions associated with systemic administration of β-blockers may occur. Abrupt withdrawal of beta-blocker may cause exacerbation of angina, and myocardial infarctions have occurred in some cases. Patients on long-term treatment (particularly in those with ischaemic heart disease) should discontinue medication gradually over a period of 1-2 wk. May mask signs and symptoms of hypoglycaemia, hyperthyroidism. Abrupt withdrawal may precipitate thyroid storm in patients suspected of developing thyrotoxicosis. Ophthalmic Timolol should not be used alone for treatment of angle-closure glaucoma. β-blocker therapy may increase sensitivity towards allergen in patients with history of atrophy or severe anaphylaxis reactions. May rarely increase muscle weakness in some patients with myasthenia gravis. Caution in patients undergoing major surgery; cerebrovascular insufficiency, heart failure, renal or hepatic impairment, pregnancy and lactation. Safety and efficacy have not been established in paediatric patients.

How to Use

Take orally with food and water, as directed by your physician.

How to Store

Keep in a cool, dry place away from sunlight and moisture.

Safety Concerns

• Alcohol: Avoid during treatment.
• Breastfeeding: Not recommended.
• Pregnancy: Contraindicated.
• Liver/Kidney: Use with caution.

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