Ripasudil (K-115) is a novel and potent Rho kinase inhibitor with intraocular pressure-lowering effect. Rho-kinase can be activated by the small GTP-binding protein Rho. Growing evidence has demonstrated that Rho/Rho-kinase pathway has been involved in a variety of cellular functions, such as actin cytoskeleton organization, vascular smooth muscle cell (VSMC) contraction, cell adhesion and motility, cytokinesis, and gene expressions. Dysfunctions of these may result in the pathogenesis of cardiovascular disease such as coronary artery spasm [1].

In vivo: In optic nerve crush (NC) C57BL/6 mice model, oral administration of K-115 (1 mg/kg/d) increased 34 ± 3% survival of RGCs after NC [2].

Clinical Trials: In the phase 1 clinical trials, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8% concentrations of K-115 increased the intraocular pressure (IOP) of healthy male adult volunteers from -1.6 mm Hg for placebo to -3.4, -2.2, -2.6, -4.0, and -4.3 mm Hg when tested in 2 hours after instillation [3]. In the phase 2 randomized clinical study, in patients with primary open-angle glaucoma or ocular hypertension, K-115 treatment (twice daily for 8 weeks) dose-dependently lowered the IOP level [4].

References:
Shimokawa H, Takeshita A.  Rho-kinase is an important therapeutic target in cardiovascular medicine[J]. Arteriosclerosis, thrombosis, and vascular biology, 2005, 25(9): 1767-1775.
Yamamoto K, Maruyama K, Himori N, et al.  The Novel Rho Kinase (ROCK) Inhibitor K-115: A New Candidate Drug for Neuroprotective Treatment in GlaucomaNovel Rho Kinase Inhibitor[J]. Investigative ophthalmology & visual science, 2014, 55(11): 7126-7136.
Tanihara H, Inoue T, Yamamoto T, et al.  Phase 1 clinical trials of a selective Rho kinase inhibitor, K-115[J]. JAMA ophthalmology, 2013, 131(10): 1288-1295.
Tanihara H, Inoue T, Yamamoto T, et al.  Phase 2 randomized clinical study of a Rho kinase inhibitor, K-115, in primary open-angle glaucoma and ocular hypertension[J]. American journal of ophthalmology, 2013, 156(4): 731-736. e2.