11.6.4 Carbonic anhydrase inhibitors and systemic drugs

Carbonic anhydrase inhibitors are sulphonamide related drugs and may give rise to associated side effects especially with systemic treatment e.g. blood disorders.

Topical carbonic anhydrase inhibitors are licensed as an adjunct to beta-blocker therapy or used alone in patients unresponsive to beta-blockers or if beta-blockers contra-indicated.

Brinzolamide can also be used as an adjunct to a prostaglandin analogue.

Systemic side effects are less compared to oral / IV acetazolamide.

Topical monotherapy

Brinzolamide
  • Eye drops 10mg/ml (£2.19 = 5ml)

Dose

  • Apply twice daily increased if necessary to 3 times daily
Dorzolamide
  • Eye drops 20mg/ml (£4.16 = 5ml)
  • Multi-dose preservative free eye drops 20mg/ml (£7.08 = 5ml)
  • Unit dose preservative free eye drops 20mg/ml (£24.18 = 60 x 0.2ml)

Dose

  • Apply three times daily

Topical combination therapy

Brinzolamide/ Brimonidine
  • Eye drops, brinzolamide 10mg/ml, brimonidine 2mg/ml (£9.23 = 5ml)

Dose

  • Apply one drop twice daily
Brinzolamide/ Timolol
  • Eye drops, brinzolamide 10mg/ml, timolol 5mg/ml (£3.36 = 5ml)

Dose

  • Apply twice daily
Dorzolamide/ Timolol
  • Eye drops, dorzolamide 20mg/ml, timolol 5mg/ml (£1.86 = 5ml)
  • Multi-dose preservative free eye drops, dorzolamide 20mg/ml, timolol 5mg/ml (£8.13 = 5ml)
  • Unit dose preservative free eye drops, dorzolamide 20mg/ml, timolol 5mg/ml (£20.95 = 60 x 0.2ml)

Dose

  • Apply twice daily

Systemic

Acetazolamide is generally used as parenteral or occasionally oral therapy for acute glaucoma. Side effects include paraesthesia, general malaise / fatigue, dizziness, electrolyte imbalance and depression. Caution is required in patients with a history of renal stones.

Acetazolamide
  • Tablets 250mg (£5.13 = 1g daily)
  • Modified-release capsules 250mg (£31.10 = 500mg daily)
  • Powder for solution for injection 500mg vials

Indications

  • Open-angle glaucoma

Dose

  • Standard-release oral or by intravenous injection, 250mg - 1g daily in divided doses
  • Modified-release, 250mg - 500mg daily

 

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