Effect of 0.04% AR-13324, a ROCK, and norepinephrine transporter inhibitor, on aqueous humor dynamics in normotensive monkey eyes.

PURPOSE: To determine the mechanism by which topically applied AR-13324, a rho kinase inhibitor, and an inhibitor of the norepinephrine transporter, reduces intraocular pressure (IOP) in normotensive monkey eyes.
METHODS: Seven normotensive monkeys were used. Tonographic outflow facility (C) was measured before drug administration and repeated 6 hours after administration of 50 µL (25 µL×2) of 0.04% AR-13324 to 1 eye and an equal volume of vehicle to the contralateral control eye. Baseline aqueous humor flow rates (F) were measured hourly for 6 hours beginning at 10:00 AM on day 1. On day 2, 50 µL (25 µL×2) of 0.04% AR-13324 was applied to 1 eye of each animal and vehicle to the fellow eye at 8:00 AM. Aqueous humor flow rates were measured at the same times as on the baseline day beginning 2 hours after dosing.
RESULTS: Six hours after a single dose of 0.04% AR-13324 to 7 normal monkey eyes, C was increased (P<0.05) by 53% in drug-treated eyes compared with either contralateral vehicle-treated control eyes or baseline measurements. The IOP measured by pneumatonometer in treated eyes was reduced (P<0.005) by 25% when compared with baseline measurements and by 24% when compared with contralateral vehicle-treated eyes. For 6 hours after a single dose of 0.04% AR-13324, F was reduced (P<0.05) by 20% and 23% when compared with contralateral vehicle-treated eyes and baseline values, respectively.
CONCLUSIONS: AR-13324 reduces IOP in normotensive monkey eyes. A dual mechanism of action, increase in tonographic outflow facility, and decrease of aqueous humor flow rates, accounts for the IOP reduction in normotensive monkey eyes.