Ripasudil does not induce phospholipid accumulation in human corneal epithelial cells

Rho-associated coiled-coil-containing protein kinase (Rho kinase; ROCK) inhibitors represent a novel class of glaucoma medications that lower intraocular pressure by enhancing aqueous humor outflow through the conventional outflow pathway. Netarsudil, a ROCK inhibitor, is known to induce cornea verticillata as an adverse effect in clinical settings. Unlike systemic amiodarone and antimalarials, topical agents do not typically induce the development of this corneal condition. This study investigated whether ripasudil, another ROCK inhibitor, induces cornea verticillata using a Chinese hamster-derived ovary cell line (CHO-K1), SV40 transformed human corneal epithelial cell line (HCE-T), and normal human primary corneal epithelial cells (HCEC-2). CHO-K1, HCE-T, and HCEC-2 were treated with ripasudil, netarsudil, or Y-27632 with varying concentrations (0.1, 0.3, 1, 3, 10, or 30 μM). Ripasudil and Y-27632 did not alter intracellular phospholipid levels at any concentration tested. Conversely, intracellular phospholipid accumulation was observed in cells treated with netarsudil. Netarsudil possesses chemical characteristics similar to those of cationic amphiphilic drugs, which are known to cause phospholipidosis. In contrast, ripasudil and Y-27632 lack these structural features. Our results suggest that ripasudil has a low likelihood of inducing cornea verticillata.