DORZOLAMIDE - A REVIEW OF ITS PHARMACOLOGY AND THERAPEUTIC POTENTIAL IN THE MANAGEMENT OF GLAUCOMA AND OCULAR HYPERTENSION

Dorzolamide (dorzolamide hydrochloride), the first topical carbonic an hydrase (CA) inhibitor to become available for clinical use, lowers in traocular pressure (IOP) by reducing aqueous humour formation. It is f ormulated as a 2% eyedrop for use in the management of glaucoma and oc ular hypertension. When administered 3 times daily, dorzolamide is eff ective in lowering IOP in patients with open-angle glaucoma or ocular hypertension. Mean IOP was reduced by approximately 4 to 6 mm Hg at pe ak (2 hours postdose) and 3 to 4.5 mm Hg at trough (8 hours postdose) in clinical trials. A 1-year comparative study showed that the ocular hypotensive efficacy of dorzolamide 2% 3 times daily was similar to th at of betaxolol 0.5% twice daily, but slightly inferior to that of tim olol 0.5% twice daily. dorzolamide has additive ocular hypotensive eff ects when used in conjunction with topical beta-adrenergic antagonists and was as effective as pilocarpine 2% 4 times daily as adjunctive th erapy in patients receiving timolol. Dorzolamide does not appear to pr oduce the acid-base or electrolyte disturbances and severe systemic ad verse events associated with oral CA inhibitors, and unlike beta-adren ergic antagonists, it is not contraindicated in patients with asthma, reactive airways disease or heart disease. Furthermore, as CA inhibito rs do not cause miosis, they may cause less interference with vision t han pilocarpine or epinephrine (adrenaline). The most common adverse e ffects associated with dorzolamide are bitter taste and transient loca l burning or stinging. conjunctivitis was the most common reason for d iscontinuation of dorzolamide in one large study. Thus, available data suggest that dorzolamide has potential as an alternative therapy opti on in patients with glaucoma or ocular hypertension who are intolerant of, or unable to receive, ophthalmic beta-adrenergic antagonists and as adjunctive therapy in patients already receiving these agents. Furt her efficacy and tolerability data are needed to determine the place o f dorzolamide in therapy.