Summary

A medication commonly used to prevent seizures in epilepsy could protect nerves in the eye from damage and also has the potential to slow the accumulation of disability in people with MS; these results were reported at the American Academy of Neurology Annual Meeting in 2015, and have now been published.

The study was a phase 2 clinical trial involving 86 people experiencing early symptoms of acute optic neuritis, often an early sign of MS. On average those who received phenytoin had 30% less damage to the nerve fiber layer in the eye compared to those who received placebo.

The study was co-funded by the National Multiple Sclerosis Society, the MS Society of the United Kingdom, the National Institute for Health Research-Clinical Research Network and University College London Hospitals Biomedical Research Center.

The team (Drs. Rhian Raftopoulos, Raju Kapoor, and colleagues, University College London) published results in The Lancet Neurology (published online January 25, 2016).

Background

This Study

Comments

: Nerve fibers, or axons, are thought to be damaged in MS in part because they can become flooded with toxic levels of sodium from the surrounding tissue as a consequence of inflammation . Phenytoin, an oral therapy that has been used extensively to treat epilepsy, was selected for this study because it blocks sodium channels, which are tiny pores that allow the passage of sodium into axons. Laboratory studies suggested that doses equivalent to those used in epilepsy may be neuroprotective.: In a Phase 2 clinical trial researchers recruited 86 people who were experiencing early symptoms of acute optic neuritis. They were randomly assigned to receive either phenytoin or a placebo for 3 months to assess whether the pill could help to protect the retina, the light-sensitive nerve layer at the back of the eye, from damage. Optic neuritis involves inflammation of the nerves carrying information between the eye and the brain, and it is often an early sign of MS.The team used medical imaging technology called optical coherence tomography (OCT) to measure the thickness of the retina at the beginning of the study and then six months later. Five participants did not complete the study. The investigators found that, of those completing the study, on average those who received phenytoin had 30% less damage to the nerve fiber layer compared to those who received placebo. Most people recover vision from their first episode of optic neuritis and in this trial this was the case for people in both groups.Treatment was generally well tolerated. Ten people in the phenytoin group had skin rashes (one severe, nine minor), resulting in treatment withdrawal.The team, Drs. Rhian Raftopoulos, Raju Kapoor (University College London) and other colleagues in the United Kingdom, published results in The Lancet Neurology (published online January 25, 2016 ).: “Protecting nerve fibers from damage during the course of MS has the potential to prevent disability, which is a key goal of MS research,” noted Dr. Kapoor. “If further studies of this or similar neuroprotective approaches are successful, it could change the future for people with MS.”“The National MS Society made a strategic investment to encourage research in the area of neuroprotection as an approach to preventing progressive disability in people with MS,” said Bruce Bebo, PhD, the Society’s Executive Vice President, Research. “It’s very encouraging to see advances in this area. An intriguing aspect of this study is that it involved repurposing a therapy already on the market, an approach that could cut years of development time and speed the use of medications for a new indication such as MS.” Read more about research to stop MS in its tracks