Additive Intraocular Pressure-Lowering Effects of Ripasudil with Glaucoma Therapeutic Agents in Rabbits and Monkeys

Abstract

Ripasudil hydrochloride hydrate (K-115), a specific Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor, is developed for the treatment of glaucoma and ocular hypertension. Topical administration of ripasudil decreases intraocular pressure (IOP) by increasing conventional outflow through the trabeculae to Schlemm's canal, which is different from existing agents that suppress aqueous humor production or promote uveoscleral outflow. In this study, we demonstrated that ripasudil significantly lowered IOP in combined regimens with other glaucoma therapeutic agents in rabbits and monkeys. Ripasudil showed additional effects on maximum IOP lowering or prolonged the duration of IOP-lowering effects with combined administration of timolol, nipradilol, brimonidine, brinzolamide, latanoprost, latanoprost/timolol fixed combination, and dorzolamide/timolol fixed combination. These results indicate that facilitation of conventional outflow by ripasudil provides additive IOP-lowering effect with other classes of antiglaucoma agents. Ripasudil is expected to have substantial utility in combined regimens with existing agents for glaucoma treatment.

Figure 1

Additive IOP-lowering effect of ripasudil with timolol. Male albino rabbits were administered 50 μL of vehicle (○), 0.4% ripasudil (●), 0.5% timolol (△), or 0.4% ripasudil + 0.5% timolol (◆) into one eye (n = 9). The contralateral eye was not treated. IOP were measured using pneumotonometers prior to the experiments and 0.5, 1, 2, 3, 4, and 5 h after instillation. For combined use of ophthalmic agents, 0.5% timolol was administered 5 min after instillation of 0.4% ripasudil. All data are presented as means ± SEs. ^∗,†P < 0.05, compared with vehicle and 0.4% ripasudil, respectively (Tukey's multiple comparison test).

Figure 2

Additive IOP-lowering effect of ripasudil with nipradilol. Rabbits were administered vehicle (○), 0.4% ripasudil (●), 0.25% nipradilol (△), or 0.4% ripasudil + 0.25% nipradilol (◆) into one eye (n = 10). IOP were measured 0.5, 1, 2, 3, 4, and 5 h after instillation. For combined use of ophthalmic agents, 0.25% nipradilol was administered 5 min after instillation of 0.4% ripasudil. All data are presented as means ± SEs. ^∗P < 0.05, compared with vehicle (Tukey's multiple comparison test).

Figure 3

Additive IOP-lowering effect of ripasudil with brinzolamide. Rabbits were administered vehicle (○), 0.4% ripasudil (●), 1% brinzolamide (△), or 0.4% ripasudil + 1% brinzolamide (◆) into one eye (n = 10). IOP were measured 0.5, 1, 2, 3, 4, and 5 h after instillation. For combined use of ophthalmic agents, 1% brinzolamide was administered 5 min after instillation of 0.4% ripasudil. All data are presented as means ± SEs. ^∗,†,‡P < 0.05, compared with vehicle, 0.4% ripasudil, and 1% brinzolamide, respectively (Tukey's multiple comparison test).

Figure 4

Additive IOP-lowering effect of ripasudil with brimonidine. Rabbits were administered vehicle (○), 0.4% ripasudil (●), 0.1% brimonidine (△), or 0.4% ripasudil + 0.1% brimonidine (◆) into one eye (n = 10). IOP were measured 0.5, 1, 2, 3, 4, and 5 h after instillation. For combined use of ophthalmic agents, 0.1% brimonidine was administered 5 min after instillation of 0.4% ripasudil. All data are presented as means ± SEs. ^∗,†,‡P < 0.05, compared with vehicle, 0.4% ripasudil, and 0.1% brimonidine, respectively (Tukey's multiple comparison test).

Figure 5

Additive IOP-lowering effect of ripasudil with latanoprost. Male cynomolgus monkeys were administered 20 μL of 0.4% ripasudil (●), 0.005% latanoprost (△), or 0.4% ripasudil + 0.005% latanoprost (◆) into one eye (n = 4). The contralateral eye was not treated. IOP were measured using pneumotonometers prior to the experiments and 1, 2, 4, and 6 h after instillation. For combined use of ophthalmic agents, 0.005% latanoprost was administered 5 min after instillation of 0.4% ripasudil. All data are presented as means ± SEs. ^∗,†P < 0.05, compared with 0.005% latanoprost and ripasudil, respectively (Tukey's multiple comparison test).

Figure 6

Additive IOP-lowering effect of ripasudil with latanoprost/timolol fixed combination. Monkeys were administered vehicle + 0.005% latanoprost/0.5% timolol fixed combination (▲), or 0.4% ripasudil + 0.005% latanoprost/0.5% timolol fixed combination (◆) into one eye (n = 5). IOP were measured before and 1, 2, 3, 4, 6, and 8 h after instillation. 0.005% latanoprost/0.5% timolol fixed combination was administered 5 min after instillation of vehicle or 0.4% ripasudil. All data are presented as means ± SEs. ^∗P < 0.05, compared with vehicle + 0.005% latanoprost/0.5% timolol fixed combination (Student's t-test).

Figure 7

Additive IOP-lowering effect of ripasudil with dorzolamide/timolol fixed combination. Monkeys were administered vehicle + 1% dorzolamide/0.5% timolol fixed combination (▲) or 0.4% ripasudil + 1% dorzolamide/0.5% timolol fixed combination (◆) into one eye (n = 5). IOP were measured before and 1, 2, 3, 4, 6, and 8 h after instillation. 1% dorzolamide/0.5% timolol fixed combination was administered 5 min after instillation of vehicle or 0.4% ripasudil. All data are presented as means ± SEs. ^∗P < 0.05, compared with vehicle + 1% dorzolamide/0.5% timolol (Student's t-test).