Objectives

To measure the effectiveness of topical 0.2% brimonidine tartrate asa suppressor of aqueous humor flow in the human eye compared with the effectivenessof 2% dorzolamide hydrochloride, and to measure the additivity of the effectsof the 2 drugs.

Design

A randomized, double-masked, placebo-controlled study was performedin 20 healthy human subjects. The topical drugs were instilled twice dailythe day before and again in the morning on the day of the measurements. Therate of aqueous humor flow was measured from 8AMto 4PMby clearance of topically applied fluorescein using a fluorophotometer,after administration of doses of each drug singly and both drugs together.Intraocular pressure (IOP) was measured with applanation tonometry.

Results

Compared with placebo, brimonidine reduced the aqueous humor flow bya mean ± SD of 28.2% ± 18.0% (P<.001),dorzolamide by 19.3% ± 22.0% (P= .007), andthe combination of brimonidine and dorzolamide by 37.2% ± 20.6% (P<.001). The combination of both drugs statisticallysignificantly suppressed aqueous humor flow compared with dorzolamide alone(P<.001) and brimonidine alone (P= .04). The IOP was reduced by a mean ± SD of 11.6% ±10.1% (P<.001) by brimonidine, 8.5% ± 14.1%(P= .02) by dorzolamide, and 17.9% ± 16.5%(P<.001) by the combination. The combination ofdrugs reduced IOP better than dorzolamide (P<.001),but not more than brimonidine (P= .06).

Conclusions

The combination of brimonidine and dorzolamide caused a further reductionof aqueous humor flow compared with each drug applied alone. The IOP was furtherreduced by the combination compared with dorzolamide alone, but not comparedwith brimonidine alone.

	Year	Citations

References