Clemastine Fumarate Partially Reverses Vision Loss From MS

By Floyd Arthur

A new study from the University of California San Francisco shows that the antihistamine clemastine fumarate (Tavist) partially reverses vision loss associated with relapsing–remitting MS. Led by Dr. Ari Green of the Multiple Sclerosis Center at UCSF, the study compared the effects of clemastine fumarate to placebo in 50 participants with MS and persistent optic neuropathy.

The researchers will present their findings at the American Academy of Neurology's 68th Annual Meeting in Vancouver, British Columbia this week.

Optic Neuritis and MS

Vision changes and pain associated with optic neuritis are a common and early sign of multiple sclerosis, and are often the first symptom for which MS sufferers seek medical care. The most commonly experienced visual disturbances include red-green color blindness, diplopia, and partial or complete blindness in one eye. These are usually accompanied by eye pain exacerbated by eye movement, peripheral and central visual field disturbances and diminished pupillary response to light.

Optic neuritis is caused by demyelinating inflammatory changes in the optic nerve. It is the presenting symptom in about 20 percent of MS diagnoses and affects about 50 percent of all patients with MS.

Treatment with high-dose intravenous methylprednisolone followed by an oral prednisone taper usually results in rapid resolution of symptoms, but has not proven to be of benefit in long term recovery of visual acuity.

Clemastine Fumarate Shows Promise

All participants in the five-month long UCSF study had chronic stable optic neuropathy with long-term loss of visual acuity. Average age of participants was 40 years, and the average duration of MS symptoms was five years.

The researchers used visual evoked potential as a measure of vision loss; included study participants had a minimum transmission delay of at least 118 milliseconds -- a biomarker for myelin loss.

For the first three months of the study, participants were randomized to either clemastine fumarate or placebo. For the second two months, the study groups were reversed.

At the end of the study, transmission delay in patients receiving clemastine fumarate was reduced by slightly less than 2 milliseconds per patient in each eye. Although modest, the improvements are considered an indicator of myelin regrowth. Said Dr. Green, “This study is promising because it is the first time a drug has been shown to possibly reverse the damage done by MS. Findings are preliminary,” he added, “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."

Clemastine fumarate is a H1 histamine agent.The major side effect experienced by study participants was fatigue.