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Efficacy of valproic acid for retinitis pigmentosa patients: a pilot study

Authors Iraha S, Hirami Y, Ota S, Sunagawa GA, Mandai M, Tanihara H, Takahashi M, Kurimoto Y

Received 6 April 2016

Accepted for publication 24 May 2016

Published 25 July 2016 Volume 2016:10 Pages 1375—1384


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Scott Fraser

Satoshi Iraha,1–5 Yasuhiko Hirami,1,2 Sachiko Ota,1,2 Genshiro A Sunagawa,3 Michiko Mandai,1–3 Hidenobu Tanihara,5 Masayo Takahashi,1–4 Yasuo Kurimoto1,2

1Department of Ophthalmology, Institute of Biomedical Research and Innovation Hospital, 2Department of Ophthalmology, Kobe City Medical Center General Hospital, 3Laboratory for Retinal Regeneration, RIKEN Center for Developmental Biology, Kobe, 4Application Biology and Regenerative Medicine, Graduate School of Medicine, Kyoto University, Kyoto, 5Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan

Purpose: The purpose of this study was to examine the efficacy and safety of valproic acid (VPA) use in patients with retinitis pigmentosa (RP).
Patients and methods: This was a prospective, interventional, noncomparative case study. In total, 29 eyes from 29 patients with RP whose best-corrected visual acuities (BCVAs) in logarithm of the minimum angle of resolution (logMAR) ranged from 1.0 to 0.16 with visual fields (VFs) of ≤10° (measured using Goldmann perimeter with I4) were recruited. The patients received oral supplementation with 400 mg of VPA daily for 6 months and were followed for an additional 6 months. BCVAs, VFs (measured with the Humphrey field analyzer central 10-2 program), and subjective questionnaires were examined before, during, and after the cessation of VPA supplementation.
Results: The changes in BCVA and VF showed statistically significant differences during the internal use of VPA, compared with after cessation (P=0.001). With VPA intake, BCVA in logMAR significantly improved from baseline to 6 months (P=0.006). The mean deviation value of the VF significantly improved from baseline to 1 month (P=0.001), 3 months (P=0.004), and 6 months (P=0.004). These efficacies, however, were reversed to the baseline levels after the cessation of VPA intake. There were no significant relations between the mean blood VPA concentrations of each patient and the changes in BCVA and VF. During the internal use of VPA, 15 of 29 patients answered “easier to see”, whereas blurred vision was registered in 21 of 29 patients on cessation. No systemic drug-related adverse events were observed.
Conclusion: While in use, oral intake of VPA indicated a short-term benefit to patients with RP. It is necessary to examine the effect of a longer VPA supplementation in a controlled study design.

Keywords: retinitis pigmentosa, valproic acid, clinical trial, retina

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