brinzolamide + timolol maleate: clinical use

Prescribing considerations

• Confirm that monotherapy has provided insufficient intraocular-pressure reduction.
• Systemic absorption can produce beta-blocker and sulphonamide-derived carbonic-anhydrase-inhibitor effects; reinforce nasolacrimal occlusion or eyelid closure.
• Review cardiovascular, respiratory, renal, hepatic, corneal, diabetic, thyroid, myasthenic and severe-allergy history.
• Safety and efficacy have not been established in children or adolescents.
• Use caution in pseudoexfoliative or pigmentary glaucoma; use in narrow-angle glaucoma is not recommended.
• Advise the anaesthetist before surgery because timolol may interact with anaesthetic medicines.

Contraindications and cautions

• Hypersensitivity to either active substance, beta blockers, sulphonamides or an excipient
• Asthma, previous asthma or severe chronic obstructive pulmonary disease
• Sinus bradycardia, sick sinus syndrome, sinoatrial block or relevant atrioventricular block without a pacemaker
• Overt cardiac failure or cardiogenic shock
• Severe allergic rhinitis
• Severe renal impairment or hyperchloraemic acidosis

Monitoring

• Intraocular pressure and treatment response
• Pulse, blood pressure and symptoms of cardiac or respiratory beta blockade where clinically indicated
• Corneal surface and dry-eye symptoms during prolonged use, particularly with compromised corneas or contact-lens use
• Skin and mucosal symptoms suggesting severe sulphonamide-associated reactions
• Acid-base disturbance or systemic carbonic-anhydrase effects in susceptible patients

Clinical pharmacology

Brinzolamide inhibits ocular carbonic anhydrase II, while timolol non-selectively blocks beta-adrenoceptors. Both chiefly reduce aqueous-humour formation. Brinzolamide and its active metabolite accumulate in red blood cells and are mainly eliminated renally; timolol is primarily metabolised through CYP2D6 and its metabolites are renally excreted.

Formulation and product differences

• The product is a white to off-white ophthalmic suspension and must be shaken before use.
• It is a multidose, preserved formulation containing benzalkonium chloride, which may irritate the ocular surface and discolour soft contact lenses.

Eye drops

Route: Ophthalmic

Strengths: 10 mg/mL + 5 mg/mL