Timolol
Antiglaucoma agents
Antiglaucoma agents
A non-selective beta-blocker eye drop that lowers eye pressure. Enough reaches the blood to slow the heart and narrow the airways.
Quick facts
- Group
- Antiglaucoma agents
- Target
- β1 and β2 adrenergic receptors
- Used for
- Open-angle glaucoma · Ocular hypertension
- Key effects
- Brief blurred vision after the drop · Eye pain
- Monitor
- Intraocular pressure · Pulse and blood pressure
- ATC
- S01ED01
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows timolol bound to the human β2 adrenergic receptor (crystal also holding cholesterol).
Timolol blocks β1 and β2 receptors without intrinsic sympathomimetic or local anaesthetic activity. In the eye its main effect is less formation of aqueous humour by the ciliary body, so intraocular pressure falls. The drug is absorbed into the bloodstream from the eye, so it can produce the same effects as an oral beta-blocker: slow heart rate, low blood pressure, heart failure and bronchospasm.
- Timolol blocks β receptors of the ciliary body
- Less aqueous humour is produced
- Intraocular pressure falls
- Drug absorbed into the blood blocks β1 (heart) and β2 (bronchi)
Indications
- Open-angle glaucoma Open-angle glaucoma →
- Ocular hypertension
- Acute angle-closure glaucoma, only together with other treatment (never on its own) Acute angle-closure glaucoma →
Adverse effects
Common
- Brief blurred vision after the drop
- Burning and stinging
- Eye pain, itching, tearing or a foreign-body feeling
- Headache and dizziness
Contraindications
- Bronchial asthma, now or in the past
- Severe COPD
- Sinus bradycardia, second- or third-degree AV block
- Overt heart failure or cardiogenic shock
- Hypersensitivity to any component
Key interactions
- Oral beta-blockers or a second beta-blocker eye drop
- Additive beta-blockade, on the eye and on the body; two topical beta-blockers are not combined
- Verapamil or diltiazem (oral or IV calcium antagonists), digoxin
- More slowing of AV conduction, low blood pressure or heart failure
- CYP2D6 inhibitors (quinidine, SSRIs)
- Stronger systemic beta-blockade, such as a slower pulse
- Epinephrine for anaphylaxis
- Patients may not respond to usual doses of epinephrine
What is monitored
- Intraocular pressure
- Pulse and blood pressure
- Wheeze or shortness of breath
- Blood glucose in diabetes
Administration and safety
- After the drop, light pressure on the inner corner of the eye (tear duct) and closed eyes for 2–3 minutes reduce the amount that reaches the blood.
- Other eye medicines are given at least 10 minutes before or after timolol.
- Soft contact lenses come out before the drop and go back in 15 minutes later.
- The surgeon and anaesthetist are told about timolol before surgery, since beta-blockade blunts heart responses.
Pregnancy and breastfeeding
There are no adequate studies in pregnant women; it is used only if the benefit justifies the risk to the fetus.
Nursing care
- Before the first dose, ask about asthma, COPD, slow pulse, heart block or heart failure.
- Check pulse and blood pressure at the start and at follow-up.
- In diabetes, explain that the racing heart of hypoglycaemia may not appear.
- Teach the patient to report wheeze, breathlessness, fainting, a slow pulse or swollen ankles.
- Teach the tear-duct pressure technique.
Pharmacokinetics
- Absorption
- Absorbed into the systemic circulation after eye drops; measurable in plasma
- Onset and duration
- The pressure-lowering effect lasts about a day; in some patients the response takes a few weeks to stabilise
Test yourself
Think of the answer, then tap the question to see it.
How does timolol lower intraocular pressure?
It reduces the production of aqueous humour by the ciliary body.
Why is timolol eye drop contraindicated in asthma?
It is absorbed into the blood and blocks β2 receptors, which can cause severe bronchospasm.
Which simple technique reduces systemic absorption of an eye drop?
Pressing on the tear duct (inner corner of the eye) and keeping the eyes closed for a few minutes.
Which heart rhythm findings contraindicate timolol?
Sinus bradycardia and second- or third-degree AV block.
Connections
← Back to the class: Antiglaucoma agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TIMOLOL MALEATE OPHTHALMIC GEL FORMING SOLUTION solution, gel forming / drops (DailyMed (U.S. National Library of Medicine), 2026); Timolol Ophthalmic: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 3D4S: Cholesterol bound form of human beta2 adrenergic receptor. (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.