Comparison of 24-hour intraocular pressure reduction with two dosing regimens of latanoprost and timolol maleate in patients with primary open-angle glaucoma

Abstract

PURPOSE: To compare the 24-hour diurnal ocular hypotensive efficacy of two dosing regimens of latanoprost, once daily (8 am or 10 pm), vs timolol maleate, twice daily.METHODS: We measured six diurnal intraocular pressure curves (6 am, 10 am, 2 pm, 6 pm, 10 pm, and 2 am) in one randomly selected eye of 34 Greek patients newly diagnosed with primary open-angle glaucoma. The first diurnal curve was an untreated baseline. Patients began taking timolol 0.5%, twice daily, for 2 months. Patients were randomly assigned to latanoprost 0.005% given at 8 am or 10 pm for 1 month and then changed to the other dosing regimen for 1 month. A diurnal curve was performed after each dosing period.RESULTS: The baseline diurnal pressure for all 34 subjects was 23.1 ± 3.7 mm Hg. The average intraocular pressures at 6 am for patients who were given latanoprost in the evening (17.9 ± 2.9 mm Hg) was statistically lower than that in patients given timolol solution (20.1 ± 2.5 mm Hg, P = .003); however, patients who were given timolol demonstrated a similar diurnal intraocular pressure (19.1 ± 2.8 mm Hg) to both morning (18.8 ± 3.7 mm Hg) and evening doses (18.8 ± 3.6 mm Hg) of latanoprost (P =.329). When the two latanoprost dosages were compared directly, evening administration provided a statistically lower intraocular pressure at 10 am (P = .0001) and morning administration at 10 pm (P = .0001). This study had an 80% power to exclude a 1.2–mm Hg difference between groups.CONCLUSIONS: This study indicates that in a small population, both latanoprost and timolol are effective in lowering intraocular pressure throughout a 24-hour period; however, latanoprost is most effective in the 12-hour to 24-hour period after administration.