brimonidine tartrate + timolol: clinical use

Prescribing considerations

• Confirm insufficient intraocular-pressure reduction with topical beta-blocker monotherapy.
• Review cardiovascular, respiratory, metabolic, psychiatric and allergy history and all systemic and ophthalmic medicines.
• Use caution in coronary disease, hypotension, first-degree heart block, peripheral circulatory disease, mild-to-moderate COPD, labile diabetes, hyperthyroidism, metabolic acidosis, untreated phaeochromocytoma, corneal disease, and hepatic or renal impairment.
• Advise punctal occlusion or eyelid closure to reduce systemic exposure.
• Tell the anaesthetist before surgery.

Contraindications and cautions

• Hypersensitivity to either active ingredient, beta blockers or an excipient
• Current or previous bronchial asthma, reactive airway disease, or severe COPD
• Sinus bradycardia, sick-sinus syndrome, sinoatrial block, relevant atrioventricular block without pacemaker control, overt heart failure, or cardiogenic shock
• Neonates and infants younger than two years
• Current MAOI therapy
• Antidepressants affecting noradrenergic transmission, including tricyclic antidepressants and mianserin

Monitoring

• Measure intraocular pressure and assess visual and optic-nerve outcomes according to the ophthalmic plan.
• Check adherence, instillation technique and punctal occlusion before concluding treatment is ineffective.
• Watch for bradycardia, hypotension, respiratory symptoms and cardiovascular deterioration.
• Assess persistent ocular redness, itching or lid inflammation for delayed hypersensitivity.
• In diabetes, reinforce that beta blockade can mask adrenergic warning signs of hypoglycaemia.

Clinical pharmacology

Brimonidine is a selective alpha-2 adrenergic agonist that reduces aqueous-humour formation and increases uveoscleral outflow. Timolol is a non-selective beta-1 and beta-2 antagonist that reduces aqueous-humour formation. Ophthalmic administration can still cause systemic alpha-adrenergic and beta-blocking effects.

Formulation and product differences

• The product is a clear, greenish-yellow multidose eye-drop solution.
• It contains benzalkonium chloride, which may irritate the eye, affect the tear film and discolour soft contact lenses.
• Discard the bottle 28 days after first opening.
• Store below 25°C and keep the bottle in its outer carton to protect it from light.

Eye drops

Route: Ophthalmic

Strengths: 2 mg/mL + 5 mg/mL