Clemastine fumarate may reverse MS-related vision damage

by Bruce Sylvester: Treatment with clemastine fumarate, an over-the-counter antihistamine used for allergies and the common cold, has partially reversed damage to the visual system in people with multiple sclerosis (MS) researchers from a preliminary study reported online on April 12, 2016, and just prior to its presentation at the American Academy of Neurology’s annual meeting.

“This study is exciting because it is the first to demonstrate possible repair of that protective coating in people with chronic demyelination from MS,” said author Ari Green, MD, assistant clinical director at the Multiple Sclerosis Center at the University of California in San Francisco. “This was done using a drug that was identified at UCSF only two-and-a-half years ago as an agent with the potential to help with brain repair.”

The investigators enrolled 50 subjects in the five-month study. They were an average age of 40 years and had been diagnosed with MS for an average of five years.

All showed evidence of stable chronic optic neuropathy, a consequence of MS, and were not recovering from a recent optic neuritis.

Subjects had vision tests at baseline and at the end of the study. For one test, called the “visual evoked potential” test, researchers measured time for transmission of signal from the subject’s retina to the visual cortex. For inclusion in the study, the protocol required evidence of delay in transmission time beyond 118 milliseconds in at least one eye, as well as evidence of a lack of adequate nerve fibers to reinsulate.

Improvement in the delay in transmission during study-related treatment  was interpreted as an indication of myelin repair.

For the first three months of the study, investigators gave subjects either the clemastine fumarate or a placebo. For the second two months, subjects who initially received clemastine fumarate received the placebo, and vice versa.

The investigators reported that delays were reduced by an average of slightly less than two milliseconds in each eye per patient among those who received the antihistamine.

“While the improvement in vision appears modest, this study is promising because it is the first time a drug has been shown to possibly reverse the damage done by MS,” said Green. “Findings are preliminary, but this study provides a framework for future MS repair studies and will hopefully herald discoveries that will enhance the brain’s innate capacity for repair.”