Purpose:
The purpose of this study was to determine the effects of olmesartan on intraocular pressure (IOP) and aqueous humor dynamics in monkeys.
Methods:
This investigator-masked crossover study was performed in 12 female cynomolgus monkeys with unilateral laser-induced glaucoma. Seated IOPs were measured in conscious animals by pneumatonometry at 8:00AM and 4:00PM on baseline day and at 4:00PM (8 hours after the 11th dose) on day 6 of twice-daily dosing with either 4% olmesartan or its vehicle. Fluorescein was given topically every five minutes until the cornea was tinted green. All measurements on day 7 of dosing were made in ketamine sedated animals. These included IOPs at 8:00AM and 11:00AM (16 hours after the 12th dose and 3 hours after the 13th dose), aqueous flow (µl/min) and outflow facility (µl/min/mmHg) by fluorophotometry, and uveoscleral outflow (µl/min) by mathematical calculation.
Results:
Data collected on the day of fluorophotometry are summarized in the table. Values are Means ± SEM. Differences between treatments were compared by two-tailed paired t-tests (p).
Conclusions:
In the normotensive eyes, when comparing drug treatment with baseline, there was a slight decrease in IOP that could not be explained by changes in inflow or outflow. In the hypertensive eyes, olmesartan significantly reduced IOP compared to baseline or vehicle treatment. Outflow facility was reduced and uveoscleral outflow was increased but these changes did not reach statistical significance. Because these effects were working against each other the IOP reduction was small.
Keywords: drug toxicity/drug effects • outflow: ciliary muscle • outflow: trabecular meshwork