Carbonic anhydrase inhibitors

Topical carbonic anydrase inhibitors are an alternative in patients resistant to or in whom betablockers are contraindicated, or where response has been inadequate. They can be alone or in addition to a beta-blocker. Carbonic anhydrase inhibitors are sulphonamide related and can give rise to associated side effects especially with oral therapy.

Dorzolamide can cause allergic conjunctivitis.

Brinzolamide has the advantage of being twice daily administration.

Azarga^® (brinzolamide/timolol) should be used second line as an alternative to dorzolamide/timolol for patients who do not tolerate dorzolamide.

Acetazolamide can be given orally or by intravenous injection as an adjunct to other treatment for reducing ocular pressure. Long-term use is not usually recommended because of side effects. These include metabolic acidosis and electrolyte imbalance, renal calculi, paraesthesia, headache and malaise, gastrointestinal upset and blood dyscrasias.