Efficacy and Safety of Branched Chain Amino Acids on Retinitis Pigmentosa: A Randomized, Double-Blind,...

The aim of this study was to investigate the efficacy and safety of orally administered branched-chain amino acids (BCAAs) on disease progression in patients with retinitis pigmentosa (RP).

A double-blind, randomized, placebo-controlled study was conducted at the Kyoto University Hospital. Seventy patients with RP aged 20 years or above were randomly assigned to the TK-98 (a combination of BCAAs in granule form) or placebo group. One packet (4.15 g) of the study drug was administered orally thrice daily for 78 weeks.

There was no significant difference in the rate of change in the total point score, the primary endpoint, between the TK-98 (-52.4 ± 10.3 dB/year) and placebo (-42.9 ± 13.8 dB/year) groups. Ellipsoid zone length decreased by -76.5 ± 8.9 and -95.5 ± 12.2 µm/year in the TK-98 and placebo groups, respectively; although this difference was not significant, the TK-98 group showed slower degeneration. No serious adverse events were associated with the oral administration of TK-98 in patients with RP.

This study did not yield conclusive evidence supporting BCAA combination granules' effectiveness in slowing visual field progression in patients with RP. An insignificant trend toward a slower reduction in ellipsoid zone length was found in morphological tests. Further studies are required to fully understand the potential benefits of BCAA supplementation in RP.

Our study demonstrates the safety of administering BCAAs to patients with RP. Accordingly, larger, more homogeneous clinical studies with longer durations may suggest their potential as therapeutic agents.