Phenytoin is an anti-convulsant drug that works on the brain and spinal cord. Its main use is in epilepsy. In MS it can be used to treat trigeminal neuralgia or other painful sensations (dysaesthesia) if other approaches have not worked.
Phenytoin has been studied as a potential neuroprotective drug. Results of a phase II study of 82 people with optic neuritis were announced at a conference in April 2015 and published in the Lancet Neurology in January 2016. Researchers found that people who had been treated with phenytoin over three months showed 30% less damage to nerve cells in the retina than people taking a placebo.
The eye and optic nerve is an accessible part of the central nervous system, which is why it is being studied closely in neuroprotection. If phenytoin can be shown to work in protecting these nerves during an optic neuritis attack, then it may turn out to be useful in protecting other nerves during and after relapses.
