dorzolamide hydrochloride + timolol maleate: clinical use

Prescribing considerations

• Systemic beta-blocker and sulfonamide-type reactions can occur despite ocular administration; punctal occlusion or eyelid closure reduces systemic exposure.
• Use caution with cardiovascular disease, hypotension, first-degree heart block, peripheral circulatory disease, mild-to-moderate COPD, hepatic impairment, diabetes prone to hypoglycaemia, hyperthyroidism, myasthenia gravis, corneal disease or previous renal stones.
• Inform the anaesthetist before surgery because ophthalmic timolol can interfere with systemic beta-agonist responses.
• Use particular caution with low corneal endothelial cell counts, chronic corneal defects or previous intraocular surgery.
• Paediatric efficacy has not been established, and safety below two years has not been established.

Contraindications and cautions

• Asthma, history of asthma or severe COPD
• Sinus bradycardia, sick sinus syndrome, sinoatrial block, relevant atrioventricular block without a pacemaker, overt cardiac failure or cardiogenic shock
• Severe renal impairment or hyperchloraemic acidosis
• Hypersensitivity to either active substance or an excipient

Monitoring

• Monitor intraocular-pressure response and glaucoma progression.
• Watch for bradycardia, hypotension, worsening cardiac or respiratory disease and masked hypoglycaemia.
• Assess persistent ocular irritation, corneal oedema, hypersensitivity or visual deterioration.

Clinical pharmacology

Dorzolamide inhibits carbonic anhydrase II and timolol blocks beta-adrenergic receptors; both reduce aqueous humour secretion. Dorzolamide accumulates in red blood cells and is eliminated mainly in urine, while ocular timolol produces measurable but low systemic exposure.

Formulation and product differences

• The selected product is preservative-free and supplied in single-use containers.
• Use each opened container immediately and discard any remaining solution.
• Keep unopened containers protected in their sachet; discard unused containers after the sachet's stated in-use period.
• The product has not been studied in contact-lens wearers.

Eye drops

Route: Ophthalmic

Strengths: 20 mg/mL + 5 mg/mL