Riluzole, often sold under the trade name Rilutek, is a medication used for the treatment of amyotrophic lateral sclerosis (ALS). ALS is a fatal neurodegenerative disease that mainly affects neurons controlling muscle movements. The drug was approved by the FDA (1995), Health Canada (1997), and the European Commission (1996). It helps slow down disease progression and may extend patient survival. The medication is available in tablet and liquid form, generally well-tolerated. There are sometimes mild side effects, which may include loss of appetite, nausea, and abdominal pain.
How does it work?
Exactly how Riluzole slows disease progression remains unknown. However, it is thought that its neuroprotective effects likely stem from reducing a phenomenon known as excitotoxicity.
Neurons communicate with each other through chemical messengers called neurotransmitters. The signalling of these messengers needs to be tightly controlled. Too little or too much signaling will disrupt normal functions of the brain and cause damage to cells. Excitotoxicity is the result of excessive signaling by glutamate, one of the most abundant neurotransmitters in the brain. Glutamate is also associated with many neurodegenerative diseases.
Riluzole prevents this excessive signaling through several mechanisms. It is hypothesized that the effectiveness of riluzole in ALS treatment is the result of this neuroprotective property.
Riluzole for Ataxia
The neuroprotective function of riluzole has been a point of interest for the treatment of other neurodegenerative diseases since its approval. Multiple clinical trials have been conducted for patients with neurodegenerative diseases including Parkinson’s disease, Huntington’s disease, multiple system atrophy, and ataxia.
In 2010, a pilot trial was conducted with 40 patients with cerebellar ataxia who showed a lower level of motor impairment, measured by the International Cooperative Ataxia Rating Scale. A follow-up trial was then performed in 2015 for 55 patients with spinocerebellar ataxia (SCA) or Friedreich’s ataxia. Similarly, patient impairment had improved by an alternative measurement using the Scale for the Assessment and Rating of Ataxia. These findings indicate the possibility of riluzole being an effective treatment for cerebellar ataxia. However, more long-term studies and ones that are specific to different types of SCA need to be conducted to confirm the results.
Riluzole in Development
Even though riluzole was discovered more than 25 years ago, variations of the drug are still under development. As ALS often affects a patient’s ability to swallow, a new formulation of riluzole that is absorbed by placing it under your tongue is being developed under the name Nurtec.
Another prodrug version of riluzole, named Troriluzole (BHV-4157), may be better absorbed by the body with fewer side effects. Troriluzole is currently in phase three clinical trial for patients with different types of SCA. The trial is expected to be complete by November 30, 2021, and will hopefully provide more insight into the effectiveness of Troriluzole in SCA patients.
Snapshot written by Christina (Yi) Peng and edited by Terry Suk.