Amiloride is a drug used in the treatment of high blood pressure and heart disease.

Early research suggested that the drug may have a neuroprotective effect in multiple sclerosis by reducing the levels of calcium and sodium that were able to pass through the nerve cell membrane and damage the axons.

Results of a pilot study in 12 people with primary progressive MS were reported in 2013. Although the numbers involved in the trial were too small to make definitive conclusions, participants experienced less damage to nerves, loss of brain volume and a slower change in Expanded Disability Status Scale (EDSS) whilst taking the drug than in the year before treatment.

Amiloride was one of three drugs studied in the MS-SMART trial, which involved 440 people with secondary progressive MS. Participants took amiloride, riluzole (a treatment for motor neurone disease), fluoxetine (used for depression) or a placebo pill for two years. MRI scans and other clinical measures such as walking, eyesight and simple thinking tests were done before and after treatment to test for signs of MS disease progression. Researchers found no clinical effect of the three drugs being tested. Although the three drugs in MS-SMART were not found to be effective, the trial was valuable in helping researchers to design clinical trials which compare several treatments to placebo at the same time. It has also enhanced our understanding of the biology of progressive MS.

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Friese MA, et al.
Acid-sensing ion channel-1 contributes to axonal degeneration in autoimmune inflammation of the central nervous system.
Nature Medicine 2007;13(12):1483-1489.
Summary (link is external)
Arun T, et al.
Targeting ASIC1 in primary progressive multiple sclerosis: evidence of neuroprotection with amiloride.
Brain 2013;136(1):106-115.
Summary (link is external)
Chataway J, et al.
Efficacy of three neuroprotective drugs in secondary progressive multiple sclerosis (MS-SMART): a phase 2b, multiarm, double-blind, randomised placebo-controlled trial.
Lancet Neurology 2020 Mar;19(3):214-225.
Full article (link is external)