Additive Intraocular Pressure-Lowering Effects of the Rho Kinase Inhibitor Ripasudil (K-115) Combined With Timolol or Latanoprost: A Report of 2 Randomized Clinical Trials.

IMPORTANCE

Ripasudil hydrochloride hydrate (K-115), a novel rho kinase inhibitor, provides statistically significant intraocular pressure (IOP)-lowering effects and has a tolerable safety profile. However, no studies have evaluated ripasudil combined with β-blockers and prostaglandin analogues.

OBJECTIVE

To evaluate the additive IOP-lowering effects and the safety of ripasudil, 0.4%, combined with timolol, 0.5%, or latanoprost, 0.005%, in patients with primary open-angle glaucoma or ocular hypertension.

DESIGN, SETTING, AND PARTICIPANTS: We conducted 2, multicenter, randomized, double-masked, parallel group comparison studies of ripasudil-timolol and ripasudil-latanoprost in 29 and 36 Japanese clinical centers, respectively. Analyses were performed on an intention-treat-treat basis. After appropriate run-in periods with timolol or latanoprost, 208 and 205 patients whose IOP levels were 18 mm Hg or higher were enrolled in the ripasudil-timolol and ripasudil-latanoprost groups, respectively. Enrollment began December 1, 2011, and follow-up was completed on September 7, 2012, in the ripasudil-timolol study. Enrollment began December 1, 2011, and follow-up was completed on September 27, 2012, in the ripasudil-latanoprost study.

INTERVENTIONS

Patients were subdivided into 2 groups in each study and were treated with ripasudil or placebo twice daily for 8 weeks.

MAIN OUTCOMES AND MEASURES

The IOP reductions in the ripasudil and placebo groups were analyzed with a repeated-measures analysis of variance model at weeks 4, 6, and 8, at trough (before instillation [9 am]) and peak (2 hours after instillation [11 am]) levels.

RESULTS

In the ripasudil-timolol study, the mean IOP reductions from baseline in the ripasudil and placebo groups were -2.4 and -1.5 mm Hg at 9 am for a difference of 0.9 mm Hg (95% CI, 0.4-1.3 mm Hg; P < .001) and -2.9 and -1.3 mm Hg at 11 am for a difference of 1.6 mm Hg (95% CI, 1.1-2.1 mm Hg; P < .001), respectively. In the ripasudil-latanoprost study, those IOP reductions were -2.2 and -1.8 mm Hg at 9 am for a difference of 0.4 mm Hg (95% CI, -0.0 to 0.9 mm Hg; P = .06) and -3.2 and -1.8 mm Hg at 11 am for a difference of 1.4 mm Hg (95% CI, 0.9-1.9 mm Hg; P < .001), respectively. The most frequently reported adverse event was conjunctival hyperemia, which was mild and in most cases resolved without treatment before the next instillation.

CONCLUSIONS AND RELEVANCE

These clinical trials found additive IOP-lowering effects of ripasudil from placebo at trough and peak levels in combination with timolol and at peak level in combination with latanoprost. However, a definitive difference in the addition of placebo to latanoprost was not identified in the trough level.

TRIAL REGISTRATION

clinicaltrials.jp Identifiers: JAPIC111700 and JAPIC111701.