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Comparison of Dorzolamide and Acetazolamide as Suppressors of Aqueous Humor Flow in Humans

1997; American Medical Association; Volume: 115; Issue: 1 Linguagem: Inglês

10.1001/archopht.1997.01100150047008

1538-3601

Todd L. Maus,

Retinal Diseases and Treatments

Objective: To compare the efficacy of topical 2% dorzolamide hydrochloride (Trusopt) as a suppressor of aqueous humor flow in the human eye with the efficacy of systemically administered acetazolamide (Diamox). Design: A randomized, double-masked, placebo-controlled study of 40 human subjects in 2 academic centers. The effect of dorzolamide on aqueous humor flow was compared with that of acetazolamide as measured by the rate of clearance of topically applied fluorescein. Results: Acetazolamide reduced aqueous flow from 3.18±0.70 (mean±SD) to 2.23±0.48 μL per minute, a reduction of 30% ( P <.001), and dorzolamide reduced the flow to 2.65±0.64 μL per minute, a reduction of 17% ( P <.001). The difference between the effect of acetazolamine and dorzolamide was significant ( P <.001). When acetazolamide is added to dorzolamide, the aqueous flow was reduced further to 2.21±0.47 μL per minute, an additional reduction of 16% ( P <.001). When dorzolamide was added to acetazolamide, no additional reduction was observed ( P =.73). Similar effects were observed for intraocular pressure. Acetazolamide reduced pressure from 12.5±2.2 (mean±SD) to 10.1±2.2 mm Hg, a decrease of 19% ( P <.001) and dorzolamide reduced it to 10.8±2.1 mm Hg, or a decrease of 13% ( P <.001). The greater effect of acetazolamide than dorzolamide was significant ( P =.03). Conclusions: For reasons that are not known, the topically applied carbonic anhydrase inhibitor 2% dorzolamide hydrochloride is not as effective as systemically administered acetazolamide. Clinicians who prescribe dorzolamide should expect less of an ocular hypotensive effect than that experienced from systemically administered acetazolamide.