Brimonidine
Antiglaucoma agents
Antiglaucoma agents
An alpha-2 agonist eye drop that lowers eye pressure two ways. It must never be used in babies under 2: it can stop their breathing.
Quick facts
- Group
- Antiglaucoma agents
- Target
- α2A adrenergic receptor
- Used for
- Open-angle glaucoma · Ocular hypertension
- Key effects
- Dry mouth · Red · Fatigue
- Monitor
- Intraocular pressure · Pulse and blood pressure
- ATC
- S01EA05
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows brimonidine bound to the human α2A adrenergic receptor in its complex with the Go protein (cryo-EM).
Brimonidine is a relatively selective α2 adrenergic agonist. It lowers intraocular pressure by reducing the production of aqueous humour and by increasing its uveoscleral outflow. The drug reaches the blood, where its central α2 effects explain the drowsiness, low blood pressure and, in infants, the depression of breathing.
- Brimonidine activates α2 receptors in the eye
- Less aqueous humour is made
- More fluid leaves by the uveoscleral route
- Absorbed drug acts on the brain: drowsiness
Indications
- Open-angle glaucoma Open-angle glaucoma →
- Ocular hypertension
Adverse effects
Common
- Dry mouth
- Red, burning or itchy eye; blurred vision
- Allergic conjunctivitis with follicles
- Fatigue, drowsiness and headache
Contraindications
- Neonates and infants under 2 years
- Hypersensitivity to any component
- Caution: depression, cerebral or coronary insufficiency, Raynaud phenomenon, orthostatic hypotension, thromboangiitis obliterans
Key interactions
- Alcohol, opioids, sedatives, anaesthetics
- Additive drowsiness and CNS depression
- Antihypertensives and cardiac glycosides
- Blood pressure may fall further
- MAO inhibitors
- May reduce brimonidine metabolism and increase hypotension (theoretical)
What is monitored
- Intraocular pressure
- Pulse and blood pressure in heart disease
- Drowsiness, especially in children
Administration and safety
- Never given to babies under 2 years.
- Other eye drops are spaced at least 5 minutes apart.
- Soft contact lenses go back in no sooner than 15 minutes after the drop (benzalkonium chloride).
- Gentle pressure on the tear duct after the drop reduces systemic absorption.
Pregnancy and breastfeeding
Animal studies showed no birth defects and human data are lacking; it is used only if the benefit justifies the risk. Breastfeeding is avoided while using it.
Nursing care
- Confirm the patient's age; in a child, report any drowsiness, slow breathing or floppiness at once.
- Warn that it can cause drowsiness: avoid driving until the effect is known, and alcohol adds to it.
- Ask about depression, Raynaud phenomenon, dizziness on standing and heart or brain circulation problems.
- Teach the patient to report rash, trouble breathing, flashes of light or blind spots.
Pharmacokinetics
- Absorption
- Reaches the blood after eye drops, with peak levels within 1–4 hours
- Metabolism
- Extensively metabolised in the liver
- Elimination
- Mainly in the urine
- Half-life
- About 3 hours in the blood
- Onset and duration
- Greatest pressure-lowering effect about 2 hours after the drop
Test yourself
Think of the answer, then tap the question to see it.
What are brimonidine's two effects on aqueous humour?
Less production and more uveoscleral outflow.
In which age group is brimonidine contraindicated, and why?
Under 2 years: infants have had apnoea, bradycardia, hypotension, hypothermia and coma.
What common systemic effect of brimonidine should a patient know about before driving?
Drowsiness and fatigue.
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 - BRIMONIDINE TARTRATE- brimonidine tartrate solution/ drops (DailyMed (U.S. National Library of Medicine), 2025); Brimonidine Ophthalmic: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 7EJ8: Structure of the alpha2A-adrenergic receptor GoA signaling complex bound to brimonidine (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.