Which medications in the drug class Carbonic anhydrase inhibitors are used in the treatment of Acute Angle-Closure Glaucoma in Emergency Medicine?

Updated: Nov 19, 2018
  • Author: Joseph Freedman, MD; Chief Editor: Steven C Dronen, MD, FAAEM  more...
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Carbonic anhydrase inhibitors

These are first-line agents that should be used immediately during the initial intervention. They reduce bicarbonate production in the ciliary epithelium and therefore decrease aqueous formation.

Acetazolamide (Diamox)

Reduces rate of aqueous humor formation by direct inhibition of enzyme carbonic anhydrase (CA) on secretory ciliary epithelium, causing, in turn, a reduction in IOP. More than 90% of CA must be inhibited before IOP reduction can occur. May reduce IOP by 40-60%. Effects are seen in about an hour, they peak in 4 h, and trough in about 12 h. Derived chemically from sulfa drugs. If one form is not well tolerated, another form may be better or lower dose of the drug may better tolerated. IV administration of this medication may be used for rapid relief of increased IOP. A beneficial effect occurs when used with miotics or mydriatics.

Methazolamide (Neptazane)

Reduces aqueous humor formation by inhibiting enzyme carbonic anhydrase, which results in decreased IOP.

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