Clemastine fumarate was first approved by the Food and Drug Administration (FDA) in 1977. It is an antihistamine medication for allergies and has been available over the counter since 1993. Its potential to treat MS is therefore as surprising as it is welcome.
According to principal investigator Dr. Ari Green, "To the best of our knowledge, this is the first time a therapy has been able to reverse deficits caused by MS. It's not a cure, but it's a first step toward restoring brain function to the millions who are affected by this chronic, debilitating disease."
The team studied the effects of clemastine fumarate on 50 individuals with long-standing MS over a 5-month period. Because the visual system is often one of the first to be affected, the researchers measured so-called visual evoked potentials (VEPs). This is a well-established method of assessing how quickly nerves conduct messages.
VEPs were measured by showing participants flickering patterns on a screen. Electrodes placed over the visual areas of the brain detected how long it took signals to travel from the eye to the relevant area of the brain.
For 90 days, half of the participants were given clemastine fumarate, and the other half received a placebo. Next, the groups were switched: the placebo group was given the drug and vice versa. Neither the participants nor the researchers knew which individuals were receiving the active treatments.