indication

For adjunctive treatment of: chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where delay of surgery is desired in order to lower intraocular pressure

pharmacology

Dichlorphenamide is an oral carbonic anhydrase inhibitor indicated for adjunctive treatment of: chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where delay of surgery is desired in order to lower intraocular pressure. Carbonic anhydrase inhibitors reduce intraocular pressure by partially suppressing the secretion of aqueous humor (inflow).

mechanism of action

Carbonic anhydrase inhibitors reduce intraocular pressure by partially suppressing the secretion of aqueous humor (inflow), although the mechanism by which they do this is not fully understood. Evidence suggests that HCO^3- ions are produced in the ciliary body by hydration of carbon dioxide under the influence of carbonic anhydrase and diffuse into the posterior chamber which contains more Na⁺ and HCO^3- ions than does plasma and consequently is hypertonic. Water is then attracted to the posterior chamber by osmosis, resulting in a drop in pressure.

drug interactions

Acetylsalicylic acid: Acetylsalicylic acid at high dose increases the effect of the carbonic anhydrase inhibitor, dichlorphenamide.

Brinzolamide: As both brinzolamide and dichlorphenamide are carbonic anhydrase inhibitors, there is an increased risk of adverse effects.The development of acid-base disorders with concurrent use of ophthalmic and oral carbonic anhydrase inhibitors has been reported. Avoid concurrent use of different carbonic anhydrase inhibitors when possible.

Memantine: Possible increased levels of memantine

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.