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January 1990

0.008% Timolol Ophthalmic SolutionA Minimal-Effect Dose in a Normal Volunteer Model

Author Affiliations

From the Wills Eye Hospital and Department of Ophthalmology (Drs Mottow-Lippa, Lippa, and Naidoff) and the Division of Clinical Pharmacology (Ms Clementi and Dr Bjornsson), Jefferson Medical College, Philadelphia, Pa, and Clinical Research and Clinical Pharmacology, Merck Sharp & Dohme Research Laboratories, West Point, Pa (Drs Lippa and Jones).

Arch Ophthalmol. 1990;108(1):61-64. doi:10.1001/archopht.1990.01070030067030

• A double-masked, randomized, placebo-controlled, rising-dose, single-dose study was undertaken to assess the effect of low concentrations of timolol maleate ophthalmic solution (0.008%, 0.025%, 0.08%, and 0.25%) on intraocular pressure and its diurnal variation in healthy, normal volunteers. A single dose of 0.008% timolol exhibits a definite but minimal-effect on intraocular pressure in this normal volunteer model, causing a significant peak mean decrease in intraocular pressure from its value immediately pre-dose. This decrease was 1.8 mm Hg (a peak mean percent decrease of 12.8%) at 2 hours postdose compared with an increase of 0.1 mm Hg (+2.5%) during a pre-study curve due to normal diurnal variation. One drop of 0.008% solution represents a single dose of approximately 2.5 μg of timolol. A slight contralateral ocular hypotensive effect appears to be present for 0.25% timolol at 2 hours postdose although it just failed to reach statistical significance.

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