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EFFICACY

Comparison of the 24-Hour Intraocular

Pressure–Lowering Effects of Latanoprost

and Dorzolamide/Timolol Fixed Combination

after 2 and 6 Months of Treatment

2
1
Anastasios G. P. Konstas, MD, PhD, Vassilios P. Kozobolis, MD, Sevasti Tsironi, MD, 1
1
1
Irene Makridaki, MD, Rallitsa Efremova, MD, William C. Stewart, MD 3,4
Purpose: To evaluate the 24-hour intraocular pressure (IOP)–lowering effect of latanoprost and the dorzo-
lamide/timolol fixed combination (DTFC) after 2 and 6 months of treatment.
Design: Randomized, prospective, crossover comparison.
Participants: Thirty-nine patients had primary open-angle glaucoma, and 14 patients had ocular hypertension.
Methods: After a 6-week washout period, patients were randomized to either 6 months of treatment with the
DTFC twice daily or latanoprost every evening and then crossed over to the opposite treatment for an additional
6 months.
Main Outcome Measure: Mean 24-hour IOP after 2 and 6 months of treatment.
Results: Fifty-three patients had an average 24-hour baseline IOP of 25.2 2.3 mmHg. After 6 months of
treatment, 24-hour IOPs were 18.1 1.9 mmHg for the DTFC and 18.3 1.9 mmHg for latanoprost. Compared
with 2 months of therapy, at 6 months the DTFC showed no significant change in mean 24-hour IOP, whereas
latanoprost demonstrated a reduction of 0.3 mmHg (P 0.01). The DTFC had more burning (P 0.001) and bitter
taste (P 0.01), whereas the latanoprost had more hypertrichosis (P 0.02).
Conclusions: After 6 months of therapy, the DTFC and latanoprost have clinically similar 24-hour IOP-
lowering efficacies. Ophthalmology 2008;115:99–103 © 2008 by the American Academy of Ophthalmology.

Over the past 3 decades, timolol maleate has been the most has been used as monotherapy or in addition to timolol
common primary monotherapy agent used to treat primary when more IOP reduction is required. 1–3 In contrast, the
open-angle glaucoma (POAG) and ocular hypertension. dorzolamide 2%/timolol maleate 0.5% fixed combination
However, more recently latanoprost 0.005% (Xalatan, (Cosopt, Merck & Co., Inc., Blue Bell, PA) was introduced
Pfizer, Inc., New York, New York), the first available pros- several years ago and also may increase ocular hypotensive
taglandin F 2 analog to reduce intraocular pressure (IOP), efficacy over timolol alone. 4–7 However, which one of these
newer therapies has significantly greater IOP control and
Originally received: August 25, 2006. safety is not yet clear.
Final revision: February 28, 2007. Fechtner et al evaluated daytime IOPs of persons dosed
Accepted: March 1, 2007. Manuscript no. 2006-960. with latanoprost each evening versus those taking the dor-
1 Glaucoma Unit, First University Department of Ophthalmology, AHEPA zolamide/timolol fixed combination (DTFC) and showed
Hospital, Thessaloniki, Greece. that diurnal pressure controls were similar with both of
8
2 Department of Ophthalmology, Democritus University of Thrace, Alex- these products. However, Konstas, Stewart, et al found
androupolis, Greece. over 24 hours that the fixed combination provided better
3 Carolina Eye Institute, School of Medicine, University of South Carolina, 24-hour pressure control ( 0.6 mmHg), mainly due to
Columbia, South Carolina. greater efficacy at 10 PM versus evening-dosed latanoprost. 9
4 PRN Pharmaceutical Research Network, LLC, Charleston, South Caro- Further, Orzalesi et al noted similar pressure controls in
lina. these 2 products except at 9 AM, when the fixed combination
Presented as a poster at: Association for Research in Vision and Ophthal- was more effective. 10 Nonetheless, despite these data the
mology meeting, April 2006, Fort Lauderdale, Florida. above studies suffered from limited population size and
The clinical sites were supported in part by an unrestricted grant from short-term follow-up.
Merck, Blue Bell, Pennsylvania. The administrative site, PRN Pharmaceu-
tical Research Network, received no financial support for the study. The purpose of this study was to evaluate the 24-hour
Correspondence and reprint requests to William C. Stewart, MD, 1 South- midterm (6 months) compared with short-term (8 weeks)
park Circle, Suite 110, Charleston, SC 29407. E-mail: info@prnorb.com. efficacy and safety of evening-dosed latanoprost versus the

© 2008 by the American Academy of Ophthalmology ISSN 0161-6420/08/$–see front matter 99
Published by Elsevier Inc. doi:10.1016/j.ophtha.2007.03.007

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