Intra-ocular pressure-lowering effects of a Rho kinase inhibitor, ripasudil (K-115), over 24 hours in primary open-angle glaucoma and ocular hypertension: a randomized, open-label, crossover study

Purpose: To investigate the intra-ocular pressure (IOP)-lowering effects of a selective Rho kinase inhibitor, ripasudil (K-115), over 24 hr in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT). Methods: In this multicenter, prospective, randomized, open-label, 3-period, Latin-square crossover clinical study, 28 patients with POAG or OHT whose IOP level was 21 mmHg or higher were subdivided into three groups. Each patient was treated with placebo and ripasudil in concentrations of 0.2 and 0.4%, at 9: 00 and 21: 00 on day 1 through a total of 3 periods separated by washout periods. IOP was measured at 9: 00, 10: 00, 11: 00, 13: 00, 16: 00, 19: 00, 21: 00, 22: 00 and 23: 00 on day 1, and 1: 00, 4: 00, 7: 00 and 9: 00 on day 2 in sitting position using Goldmann applanation tonometer. Main outcome measure was the IOP reduction of placebo and ripasudil from baseline. Results: The mean IOP reduction was -5.2 mmHg for 0.2%, -6.4 mmHg for 0.4% and -2.0 mmHg for placebo at 2 hr after the first instillation. Also, the corresponding values were -6.8 mmHg for 0.2%, -7.3 mmHg for 0.4% and -4.1 mmHg for placebo at 2 hr after the second instillation. Statistically significant IOP reduction, compared with placebo, was found for both 0.2 and 0.4% from 1 through 7 hr after each instillation. In safety, conjunctival hyperaemia was observed in 22 patients (79%) for 0.2%, 27 patients (96%) for 0.4% and three patients (11%) for placebo. Conclusion: Ripasudil is a promising new topical medication to lower IOP for at least 7 hr after instillations in patients with POAG or OHT.