Valproic Acid May Stop Vision Loss in Retinitis Pigmentosa
The drug valproic acid, which has been approved by the Food and Drug Administration (FDA) for treatment of seizures, migraines, and bipolar disorder, also appears to stop vision loss associated with retinitis pigmentosa (RP). This eye disease often results in legal blindness by age 40.
Retinitis pigmentosa is a term used to describe a group of inherited diseases that cause degeneration of the retina, the part of the eye that captures images from the visual field. In retinitis pigmentosa, cells in the retina called rods and cones die. Typically rods are affected first, which impacts peripheral and night vision. When the cones are involved, people lose color perception and central vision.
According to the Foundation Fighting Blindness, approximately 100,000 people in the United States have retinitis pigmentosa. Depending on the gene mutations a person inherits, he or she can develop any one form of retinitis pigmentosa or a related disease, such as Usher syndrome, Leber’s congenital amaurosis, or rod-cone disease, among others.
At the University of Massachusetts Medical School (UMMS), a team of scientists discovered a new potential therapeutic link between valproic acid and retinitis pigmentosa. According to Shalesh Kaushal, MD, PhD, chair of ophthalmology and associate professor of ophthalmology and cell biology at UMMS, “inflammation and cell death are key components of RP. It appears the valproic acid protects photoreceptor cells from this.”
Kaushal and his team have conducted retrospective studies in which patients with retinitis pigmentosa were given doses of valproic acid ranging from 500 to 750 mg daily over two to six months. The patients were treated at a time in their disease course when individuals normally experience rapid vision loss. Instead, 60 percent of the patients in the study experienced an improvement in their vision.
Based on these and other findings, UMMS will be the coordinating site for a three-year clinical trial funded by the Foundation Fighting Blindness/National Neurovision Research Institute that will quantify the potential of valproic acid as a treatment for RP.
Because more than 40 different genes have been linked to retinitis pigmentosa, finding a treatment for the disease has been challenging. Valproic acid has a unique profile that makes it a possible candidate for effective treatment. Kaushal notes that finding new purposes for drugs that already have FDA approval, such as valproic acid, “is an economical and time-efficient way to quickly bring new treatments to patients.”
Steve Bramer, PhD, chief drug development officer of the National Neurovision Research Institute, believes valproic acid “has the potential to preserve vision for thousands of people affected by retinal diseases.” Many people with retinitis pigmentosa and related diseases that cause vision loss will be looking forward to the results of the upcoming trials.
Foundation Fighting Blindness
University of Massachusetts Medical School