Description: Timolol maleate eye drops is a non-selective beta-adrenergic receptor blocking agent. It is a white, odorless, crystalline powder which is soluble in water, methanol, and alcohol. Timolol maleate eye drops is stable at room temperature.Its chemical name is (-)-l -(tert-butylamino)-3-[ (4-morpholino-l,2,5-thiadiazol-3-yl) oxy]-2-propanol maleate (1:1) (salt) . Timolol maleate eye drops is supplied as a sterile, isotonic, buffered, aqueous solution.

Pharmacological effects: Timolol maleate is a betal and beta2 (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. Beta-adrenergic receptor blockade reduces cardiac output in both healthy subjects and patients with heart disease. In patients with severe impairment of myocardial function, beta-adrenergic receptor blockade may inhibit the stimulatory effect of the sympathetic nervous system necessary to maintain adequate cardiac function.Beta-adrenergic receptor blockade in the bronchi and bronchioles results in increased airway resistance from unopposed parasympathetic activity. Such an effect in patients with asthma or other bronchospastic conditions is potentially dangerous. Timolol maleate eye drops, when applied topically on 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. The higher the level of intraocular pressure, the greater the likelihood of glaucomatous visual field loss and optic nerve damage.

Pharmacokinetics: The onset of reduction in intraocular pressure following administration of Timolol maleate eye drops can usually be detected within one-half hour after a single dose. The maximum effect usually occurs in one to two hours and significant lowering of intraocular pressure can be maintained for periods as long as 24 hours with a single dose. The mean peak plasma concentration following morning dosing was 0.46 ng/mL and following afternoon dosing was 0.35 ng/mL.Repeated observations over a period of one year indicate that the intraocular pressure-lowering effect of Timolol maleate eye drops is well maintained.

Indications: Timolol maleate eye drops is indicated in the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.

Precautions: Because of potential effects of beta-adrenergic blocking agents on blood pressure and pulse, these agents should be used with caution in patients with cerebrovascular insufficiency.Timolol maleate eye drops should not be used alone in the treatment of angle-closure glaucoma.While taking beta-blockers, patients with a history of atopy or a history of severe anaphylactic reactions to a variety of allergens may be more reactive to repeated accidental, diagnostic, or therapeutic challenge with such allergens. Such patients may be unresponsive to the usual doses of epinephrine used to treat anaphylactic reactions. Patients with bronchial asthma, a history of bronchial asthma, severe chronic obstructive pulmonary disease, sinus bradycardia, second or third degree atrioventricular block, or cardiac failure should be advised not to take this product.

Adverse reaction: The most frequently reported adverse experiences have been burning and stinging upon instillation.