Timolol

Timolol maleate

Ophthalmic Beta-blocker (Non-selective)TopicalDogsCats

Also known as: Azarga · CoSopt · Timoptol · Timololum

Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference

One drop per affected eyetopical· q8-12h

Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.

Dosing by species

🌎 NA — North America🌍 EU — Europe

Dogs

Indication	Dose	Route	Frequency	Duration	Region
Glaucoma	One drop per affected eye	topical	q8-12h	—	🌍 EU

Glaucoma: Can be used alone or in combination with dorzolamide/brinzolamide

Cats

Indication	Dose	Route	Frequency	Duration	Region
Glaucoma	One drop per affected eye	topical	q12h	—	🌍 EU

Glaucoma: Dorzolamide alone reaches maximal IOP lowering efficiency in cats

Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.

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Overview

Timolol is a topical non-selective beta-blocker primarily used for the management of canine and feline glaucoma. It can be used as a monotherapy or in combination with other topical glaucoma drugs, such as carbonic anhydrase inhibitors (e.g., dorzolamide or brinzolamide).

Clinical Warning: Timolol causes miosis and may therefore not be the drug of choice in uveitis, anterior lens luxation, or pupil block. Systemic absorption can occur, leading to cardiovascular effects.

Mechanism of action

Timolol acts as a non-selective beta-adrenergic receptor antagonist. It decreases aqueous humour production via beta-adrenoreceptor blockade in the ciliary body, which subsequently lowers intraocular pressure (IOP).

Safety & warnings

Contraindications

Uncontrolled heart failure
Asthma
Uveitis
Anterior lens luxation
Pupil block

Adverse effects

Miosis
Conjunctival hyperaemia
Local ocular irritation
Bradycardia (systemic)
Hypotension (systemic)

Precautions

Normal precautions should be observed for safety and handling.

Systemic Absorption: Be aware that topical application can lead to systemic absorption, potentially causing bradycardia and reduced blood pressure. Use with caution in small patients or those with pre-existing cardiovascular or respiratory disease.

Drug interactions

Oral beta-blockersMajor

Additive adverse effects (bradycardia, hypotension)

Calcium antagonistsMajor

Prolonged AV conduction times

DigoxinMajor

Prolonged AV conduction times

Monitoring

Intraocular pressure (IOP)
Heart rate and rhythm
Blood pressure

Pharmacokinetics

Absorption

Absorbed locally into the eye; systemic absorption can occur via the nasolacrimal duct and conjunctival vessels.

Distribution

Distributes well into ocular tissues.

Metabolism

Systemically absorbed drug is metabolized in the liver.

Elimination

Excreted primarily via the kidneys if systemically absorbed.

Overdose

Overdosage via topical application is rare but may lead to exacerbated systemic effects such as bradycardia, hypotension, and bronchospasm. Treatment is supportive and symptomatic. Excess topical product should be flushed from the eye with sterile saline.

Available products

Formulations

0.25% ophthalmic solution
0.5% ophthalmic solution
1% brinzolamide / 0.5% timolol ophthalmic suspension (Azarga)
2% dorzolamide / 0.5% timolol ophthalmic solution (CoSopt)

Human-labeled

Azarga (1% brinzolamide/0.5% timolol)
CoSopt (2% dorzolamide/0.5% timolol)
Timoptol (0.25%, 0.5% solutions)
Timolol generic solutions

Regulatory status

United States✓ ApprovedPrescription onlyFDA

Human approved products used off-label in veterinary medicine.

European Union✓ ApprovedPrescription onlyEMA

POM (Prescription Only Medicine)

United Kingdom✓ ApprovedPrescription onlyVMD