Alpha-2 Adrenergic Agonist Pregnancy: Safety in human pregnancy not established — should only be used during pregnancy if the potential benefit to the mother outweighs the potential risk to the foetus. Not teratogenic in animals, but increased preimplantation loss and postnatal growth reduction seen in rabbits at supratherapeutic plasma levels. Should not be used by women nursing infants (SPC 4.6).

Brimonidine

Brand names: Alphagan, Combigan (with timolol), Mirvaso (for rosacea)

Brimonidine is a selective alpha-2 adrenergic agonist used as a topical ocular hypotensive agent in open-angle glaucoma and ocular hypertension.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One drop into the affected eye(s)

Route: Ocular (topical eye drops)

Frequency: Twice daily, approximately 12 hours apart

Source: eMC SPC for 'Brimonidine Tartrate 0.2% w/v Eye Drops'. Adults including the elderly — no dosage adjustment is required in elderly patients. To reduce possible systemic absorption, compress the lachrymal sac at the medial canthus (punctal occlusion) for one minute immediately after instillation of each drop. If more than one topical ophthalmic drug is to be administered, instil them 5 to 15 minutes apart. Renal/hepatic impairment: brimonidine eye drops have not been studied in these patients. Paediatric population: no clinical studies have been performed in adolescents (12 to 17 years); brimonidine eye drops should not be used in children aged below 12 years and are contraindicated in neonates and infants (less than 2 years of age); safety and efficacy in children has not been established. Children of 2 years and above, especially 2 to 7 years and/or weighing 20 kg or less, should be treated with caution and closely monitored due to the high incidence and severity of somnolence (SPC 4.2/4.4). NOTE: the US label in the source bundle is LUMIFY Redness Reliever Eye Drops (an OTC ocular redness product) — a different indication and strength, so it was not used for this dose.

Dose adjustments

Renal

Not studied in patients with renal (or hepatic) impairment — caution should be exercised when treating such patients (SPC 4.2/4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Neonates and infants
Patients receiving monoamine oxidase (MAO) inhibitor therapy
Patients on antidepressants which affect noradrenergic transmission (e.g. tricyclic antidepressants and mianserin)

Side effects

Oral dryness, ocular hyperaemia and burning/stinging — very common (each 22 to 25% of patients)
Ocular irritation including allergic reactions (hyperaemia, burning, stinging, pruritus, foreign body sensation, conjunctival follicles), allergic blepharitis/conjunctivitis and blurred vision — very common (ocular allergic reactions in 12.7% of trial subjects, causing withdrawal in 11.5%)
Headache and drowsiness — very common; fatigue — very common
Dizziness, abnormal taste, asthenia, upper respiratory symptoms — common
Palpitations/arrhythmias including bradycardia and tachycardia, systemic allergic reactions and depression — uncommon

Interactions

MAO inhibitors and antidepressants affecting noradrenergic transmission (tricyclics, mianserin) — contraindicated
CNS depressants (alcohol, barbiturates, opiates, sedatives or anaesthetics) — possible additive or potentiating effect
Drugs affecting the metabolism and uptake of circulating amines (e.g. chlorpromazine, methylphenidate, reserpine) — caution advised
Antihypertensives and/or cardiac glycosides — caution, as clinically insignificant decreases in blood pressure have been reported after application
Caution when initiating or changing the dose of a concomitant systemic agent that may interact with alpha-adrenergic agonists or interfere with their activity

Clinical monograph

How it works

It lowers intraocular pressure by reducing aqueous humour production and increasing uveoscleral outflow via stimulation of alpha-2 receptors in the ciliary body.

Prescribing in practice

Avoid in neonates and young infants, in whom systemic absorption can cause CNS depression, apnoea, bradycardia and hypotension.
Commonly causes ocular allergy and conjunctival hyperaemia, which may necessitate discontinuation with prolonged use.
Use with caution in cardiovascular disease, cerebral or coronary insufficiency, depression, and orthostatic hypotension.

Monitoring

Monitor intraocular pressure response and watch for local hypersensitivity and, in susceptible patients, systemic alpha-adrenergic effects such as drowsiness and dry mouth.

Counselling the patient

It can cause drowsiness and fatigue; take care when driving or operating machinery.
Remove soft contact lenses before instilling and wait before reinserting them.
Report persistent redness, itching or swelling of the eye, which may indicate an allergic reaction.

Evidence & guidelines

Topical alpha-2 agonists are an established second-line option for lowering intraocular pressure where prostaglandin analogues or beta-blockers are insufficient or unsuitable.

Reference: RCOphth Glaucoma Guidelines; MHRA Brimonidine Paediatric Warning; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

FAST Exam Protocol — Focused Assessment with Sonography in Trauma · Trauma

Drugs

Pathways