Latanoprost More Effective Than Timolol at Lowering Intraocular Pressure

Laurie Barclay, MD

February 11, 2004

Feb. 11, 2004 -- Latanoprost was more effective than timolol at lowering intraocular pressure (IOP), according to the results of a randomized crossover study published in the February issue of the Archives of Ophthalmology.

"Latanoprost, a phenyl-substituted prostaglandin analogue, has been studied extensively for its [IOP]-lowering efficacy and adverse effects in cases of primary open-angle glaucoma," write Ramanjit Sihota, MD, FRCS, from the All India Institute of Medical Sciences in New Delhi, and colleagues. "To our knowledge, no long-term, crossover study has evaluated latanoprost and timolol with respect to their efficacy in cases of chronic primary angle-closure glaucoma."

In this masked, prospective study, 30 patients with bilateral chronic primary angle-closure glaucoma after laser iridotomy were randomized to three months of treatment with latanoprost once daily or timolol twice daily. This was followed by a one-month washout period, then by three months of treatment with the other drug. The investigators recorded the circadian rhythm of IOP before the start of therapy, at three months, and at seven months.

Mean IOP was 23.5 ± 2.1 mm Hg at baseline, and it decreased by 8.2 ± 2.0 mm Hg after latanoprost treatment ( P < .001) and by 6.1 ± 1.7 mm Hg after timolol treatment ( P = .01). The decrease in IOP was significantly greater after latanoprost treatment ( P < .001).

Latanoprost was more effective in eyes having morning and afternoon peaks of IOP than in eyes without clear circadian rhythm of IOP. Reduction of more than 30% from baseline IOP occurred in 43 eyes (72%) of patients receiving latanoprost and in 26 eyes (43%) of patients receiving timolol.

"There were greater mean and peak IOP reductions achieved with 0.005% latanoprost once daily compared with 0.5% timolol twice daily," the authors write. "It is important to schedule the follow-up of glaucoma patients around the time that the highest IOP is expected.... Latanoprost was clinically more effective than timolol because it lowered the IOP to a greater extent and dampened the circadian rhythm of IOP."

The authors report no relevant financial interest in this study.

Arch Ophthalmol. 2004;122:185-189

Reviewed by Gary D. Vogin, MD