Ripasudil hydrochloride hydrate: targeting Rho kinase in the treatment of glaucoma

INTRODUCTION: Among the intraocular pressure (IOP)-lowering drugs used in a clinical setting, Rho kinase (ROCK) inhibitors lower IOP by a unique mechanism, namely the depolymerization of intracellular actin in the conventional outflow tissues: the trabecular meshwork (TM) and Schlemm's canal (SC). Furthermore, ROCK inhibitors suppress the production of extracellular matrix by TM cells, which represents a potential alternative method of lowering IOP. Considering that conventional outflow is a dominant pathway in humans, IOP-lowering ROCK inhibitors, delivered in conjunction with other drugs, may be able to treat the glaucomatous eye. Areas covered: Ripasudil hydrochloride hydrate is the first ROCK inhibitor approved for clinical use in Japan (and worldwide) against glaucoma and ocular hypertension. The efficacy of ripasudil, as monotherapy and as an adjunctive medication to prostaglandin analogs and/or adrenergic β-receptor antagonists, has been confirmed in clinical trials. Expert opinion: Considering the unique ROCK-inhibiting mechanism by which ripasudil lowers IOP via its actions on TM and SC endothelial cells, it may be an ideal adjunctive medication for treating glaucoma in the clinic.