Common Antihistamine Could Reverse Optic Neuropathy in Multiple Sclerosis

Optic neuropathy is common in multiple sclerosis as the immune system destroys myelin and damages the nerves.

A 5-month study showed a common over-the-counter antihistamine could reverse optic neuropathy in multiple sclerosis (MS) patients.

Optic neuropathy is common in MS patients because the immune system destroys myelin causing damage to the nerves, resulting in the slowing of signals to and from the brain.

They study enrolled 50 MS patients with an average age of 40-years-old, who have had an MS diagnosis for an average of 5 years and also had mild disability. Each participant showed evidence of stable chronic optic neuropathy (were not recovering from recent optic neuritis).

During the study, patients were given vision tests at both the beginning and end of the study. Visual-evoked potential recorded the time for transmission of a signal from the retina to the visual cortex.

In order to be eligible for the study, participants were required to have a delay in transmission beyond 118 milliseconds in at least 1 eye and also show evidence of an adequate number of nerve fibers to reinsulate. A biomarker of myelin repair was defined as an improvement in the delay of transmission.

For the first 3 months participants were given the clemastine fumarate or a placebo, and for the second 2 months, patients who were given the drug received the placebo or vice versa.

The study’s findings, presented at the 68th Annual Meeting of the American Academy of Neurology, showed that patients who received the antihistamine saw delays that were reduced by an average of slightly less than 2 milliseconds in each eye for each patient.

“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 study author Ari Green, MD. “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.”

Common adverse events were a modest increase in fatigue while taking the antihistamine. Investigators stressed that more research is needed with a larger group of MS patients before clemastine fumarate can be recommended by doctors.

“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,” Green said. “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.”