Common antihistamine may provide a clue in treatment for multiple sclerosis

Common antihistamine may provide a clue in treatment for multiple sclerosis

A familiar antihistamine, bought by consumers to relieve the symptoms of allergies and the common cold, helped to partly reverse damage to the eyes in people with multiple sclerosis (MS), according to a recent preliminary study.

"Whether this drug can really repair the optic nerve or not during acute optic neuritis attacks needs to be answered in Phase III studies with more patients."

Clemastine fumarate is an antihistamine commonly used to block central and peripheral H1 histamine sites and thereby minimize the symptoms of allergies. As is common with antihistamines, it does have anticholinergic side effects.

The study's 50 subjects had optic neuritis, which can occur in patients with multiple sclerosis when the myelin insulating the optic nerve is attacked by inflammatory cells of the body. Symptoms include blurriness in the central visual field, decreased contrast and color sensitivity and vision loss. The loss of myelin causes the conduction velocity from the retina to the visual cortex to be slower.

The results of the preliminary study were presented at the annual meeting of the American Academy of Neurology (AAN) in April.

"This study is exciting because it is the first to demonstrate possible repair of that protective coating in people with chronic demyelination from MS," study author and AAN member Ari Green, M.D., assistant clinical director of the Multiple Sclerosis Center at the University of California, San Francisco (UCSF), told Science Daily. "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 study covered five months among patients who had mild disability and had been diagnosed about five years prior. For the first three months, study participants were given clemastine fumarate or a placebo. Over the next two months, participants switched "treatments." The results were then studied.

"During the study, delays were reduced by an average of slightly less than two milliseconds in each eye per patient among those who received the antihistamine," according to Science Daily.

These preliminary results do potentially open up new treatment avenues, says Michael Earley, O.D., Ph.D., associate dean of academic affairs at The Ohio State University College of Optometry and a member of the AOA's Health Promotions Committee.

But Dr. Earley noted the efficacy of clemastine as a treatment had not yet been proven.

"Whether this drug can really repair the optic nerve or not during acute optic neuritis attacks needs to be answered in Phase III studies with more patients," Dr. Earley says. "These preliminary results have to be given proper consideration in the context of this clinical trial. This work has not been published yet or replicated; the AAN chose to go for a press release, ahead of the publication."

He adds, "The primary efficacy endpoint, latency delay on visual evoked potential, was reduced by 1.9 ms/eye for the period of treatment with clemastine (P = .003). However, there is no other means to evaluate if this represents real remyelination or just functional improvement. The other functional endpoint was trending but not significant. They reported worsened fatigue."

Dr. Earley also spoke with experts in the treatment of multiple sclerosis for this story. They agreed that the evidence needed to be stronger regarding clemastine.

"So I think at best the results open speculation about future treatment but the available evidence falls short of providing enough evidence for altered care," Dr. Earley says.

The AOA follows all research closely, including potential multiple sclerosis treatments. Although clemastine fumarate is an interesting treatment possibility for patients, more research is needed regarding its influence on visual health. For more information or help for better vision, please visit the AOA website.

May 6, 2016

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