Valproic acid no better than placebo for autosomal dominant retinitis pigmentosa

Posted on: Tuesday 11 September 2018

The results of a clinical trial did not provide support for the use of orally administered valproic acid for the treatment of autosomal dominant retinitis pigmentosa, as it did not outperform a placebo over the course of 12 months.
The multicentre, prospective, interventional, placebo-controlled, double-masked, randomised phase II clinical trial included 90 participants who received either 500 mg to 1,000 mg of oral valproic acid (VPA) daily or a placebo for 12 months. Researchers evaluated the change in visual field area between baseline and one year as the primary outcome measure.

Seventy-nine subjects completed the full trial, with 42 receiving a placebo and 37 receiving VPA. In the placebo arm, the mean change between baseline and 12 months in kinetic perimetry visual field area averaged –122.9 degree2 in the right eye and –112 degree2 in the left eye compared with the mean change of –293.7 degree2 in the right eye and –237.1 degree2 in the left eye for the VPA arm. The difference between the arms for mean change in kinetic perimetry visual field area was –150.43 degree2, which was statistically significantly worse for the VPA group.

“While valproic acid, a U.S. Food and Drug Administration-approved drug with a black-box warning, made the progression of visual fields deteriorate faster than those in the placebo group, if this study had not been done the patient population would have been left with the results of the published, positive-finding pilot trial and many patients would have gone on to use this medication off-label, likely with significant potential risk,” said Stephen Rose, PhD, a co-author of the study.