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Additive Intraocular Pressure Reduction Effect of Fixed Combination of Maleate Timolol 0.5%/Dorzolamide 2% (Cosopt) on Monotherapy With Latanoprost (Xalatan) in Patients With Elevated Intraocular Pressure: A Prospective, 4-week, Open-label, Randomized, Controlled Clinical Trial

Hatanaka, Marcelo MD; Reis, Alexandre MD; Sano, Milena Eimi MD; Susanna, Remo Jr MD

doi: 10.1097/IJG.0b013e3181b4cab4
Original Studies

Purpose: To evaluate the additive effect of dorzolamide/timolol fixed combination in patients under monotherapy with latanoprost.

Patients and Methods: In this prospective, 4-week, randomized, open-label controlled clinical trial, patients with open-angle glaucoma or ocular hypertension, which presented at least 15% intraocular pressure (IOP) reduction after a minimum period of 15 days of monotherapy with latanoprost and whose IOP level was considered above the established target-IOP level were randomized to receive fixed combination of timolol/dorzolamide twice daily in one of eyes. The fellow eye was kept under monotherapy and was included in the control group. A modified diurnal tension curve (mDTC) followed by the water drinking test were performed in the baseline and week 4 visits to evaluate IOP profile between groups.

Results: Forty-nine per-protocol patients were analyzed. After latanoprost monotherapy run-in period, IOP levels were significantly reduced (P<0.001) in both control and study groups to 15.34±2.96 mm Hg and 15.24±2.84 mm Hg (30.8% and 32.2% IOP reduction, respectively; P=0.552). At week 4, mean baseline diurnal IOP levels were 15.60±3.09 and 14.44±3.03 (7.4% difference; P=0.01). Mean baseline IOP modified diurnal tension curve peak after latanoprost run-in period were 17.47±3.68 mm Hg and 17.02±3.35 mm Hg (control and study eyes, respectively; P=0.530). At week 4 visit, mean water-drinking test peaks were significantly reduced in the study eye group in comparison with the control group: 19.02±3.81 mm Hg and 20.39±4.19 mm Hg, respectively (6.7% reduction; P=0.039).

Conclusions: In our sample, dorzolamide 2%/timolol 0.5% fixed combination as add-on therapy in patients with open-angle glaucoma or ocular hypertension under monotherapy with latanoprost with IOP already in mid-teens levels may further enhance pressure reduction.

Department of Ophthalmology, School of Medicine, University of Sao Paulo, Brazil

This study was performed with unrestricted financial support from Merck and Co Inc.

Reprints: Marcelo Hatanaka, MD, Department of Ophthalmology, School of Medicine, University of São Paulo, Brazil (e-mail:

Received for publication December 5, 2008

accepted June 20, 2009

The study was approved by the local ethics committee for each study site and performed in accordance with the ethical standards adopted by the 1964 18th World Medical Assembly in Helsinki, Finland, and with later revisions.

© 2010 Lippincott Williams & Wilkins, Inc.