Abstract
Purpose :
Ripasudil is one of the strong Rho-associated protein kinase inhibitors (ROCK- inhibitor). Inhibition of ROCK activity alters in trabecular meshwork cellular responses and improves the outflow facility. Pilocarpine retracts the trabecular meshwork and enhances the aqueous outflow which is the different mechanism from ripasudil to increase outflow. Timolol decrease the aqueous inflow and decrease intraocular pressure (IOP). The combination of the different kind of IOP lowering mechanism might enhance the IOP decrease. The purpose of this study is to examine the changes of ocular hypotensive effect of ripasudil combined with pilocarpine or timolol in rabbits.
Methods :
IOP was monitored using a Tono Lab in albino rabbits for 5 hours. We topically applied one drop of saline, 0.4% ripasudil, 0.5% timolol or 2% pilocarpine alone to the 8 rabbits. We also combined 0.4% Ripasudil with 0.5% timolol or 2% pilocarpine to observe the combination effect on IOP. The IOP after application of the saline was served as a control. Repeated-measures analysis of variance and Dunnett's post-hoc tests were used for the statistical analyses.
Results :
After topical instillation of 0.4% ripasudil, 0.5% timolol showed significant IOP decrease compared to saline group. IOP difference between control and ripasudil was14.2 mmHg and between control and timolol was 5.7 mmHg at 30 minutes after application. Pilocarpine group did not show any IOP difference compared to saline group. Adding the timolol or pilocarpine did not change the IOP lowering effect of ripasudil.
Conclusions :
Ripasudil could not enhance the IOP lowering effect of ocular hypotensive agents with the same action point, but with different mechanism (pilocarpine) and different action point (Timolol) in normal albino rabbits.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.