Timolol maleate

How it works

By blocking beta-adrenoceptors in the ciliary epithelium it reduces the production of aqueous humour, thereby lowering intraocular pressure.

Prescribing in practice

• Despite topical administration, systemic absorption can produce beta-blockade, so it is contraindicated in asthma, a history of obstructive airways disease and in bradycardia, heart block or uncontrolled heart failure.
• Use with caution alongside systemic beta-blockers or other drugs that slow the heart, as additive effects can occur.
• Nasolacrimal occlusion or gentle eyelid closure after instillation reduces systemic absorption.

Monitoring

Monitor intraocular pressure for treatment response and remain alert for systemic effects such as bradycardia or bronchospasm, particularly in at-risk patients.

Counselling the patient

• Press gently on the inner corner of the eye and close the eyelids for a short time after instilling to limit absorption into the body.
• Report wheeze, breathlessness, a slow or irregular heartbeat or unusual tiredness.
• Continue using regularly as glaucoma usually causes no symptoms.

Evidence & guidelines

Topical beta-blockers are an established option for lowering intraocular pressure in glaucoma per NICE guidance, with well-recognised respiratory and cardiac contraindications.