Neuroprotection With Phenytoin in Optic Neuritis

Summary

Optic neuritis is caused by inflammation of the optic nerve and causes loss of vision in the affected eye. It is often associated with multiple sclerosis. Loss of vision after an attack of optic neuritis is caused by damage to the nerve fibres in the optic nerve. There are a number of factors that contribute to nerve fibre damage including increased levels of sodium within them, so blocking sodium entry could help to protect them against damage. The purpose of this study is determine whether phenytoin (which blocks sodium entry into cells) can protect against loss of nerve fibres and prevent loss of vision after optic neuritis.

Timeline

Start

2011-11

Primary completion

2014-12

Completion

2015-03

Publications

• Kodali S, Bianchi A, Raftopoulos R, Moccia M, Malladi AP, Yiannakas MC, Fugger M, Samson RS, Wheeler-Kingshott CAM, Koltzenburg M, Prados F, Hickman S, Kapoor R, Toosy AT. Effects of Phenytoin on the Retinal Ganglion Cell-Inner Plexiform Layer in Acute Optic Neuritis: Analysis of a Phase II Randomized Trial. Neurology. 2025 Oct 21;105(8):e213951. doi: 10.1212/WNL.0000000000213951. Epub 2025 Sep 25.
• Raftopoulos R, Hickman SJ, Toosy A, Sharrack B, Mallik S, Paling D, Altmann DR, Yiannakas MC, Malladi P, Sheridan R, Sarrigiannis PG, Hoggard N, Koltzenburg M, Gandini Wheeler-Kingshott CA, Schmierer K, Giovannoni G, Miller DH, Kapoor R. Phenytoin for neuroprotection in patients with acute optic neuritis: a randomised, placebo-controlled, phase 2 trial. Lancet Neurol. 2016 Mar;15(3):259-69. doi: 10.1016/S1474-4422(16)00004-1. Epub 2016 Jan 26.
• Counihan TJ, Duignan JA, Gormley G, Saidha S, Dooley C, Newell J. Does long-term partial sodium channel blockade alter disease progression in MS? Evidence from a retrospective study. Ir J Med Sci. 2014 Mar;183(1):117-21. doi: 10.1007/s11845-013-1042-7. Epub 2013 Nov 28.

Drugs

Indications