riluzole

Riluzole

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">riluzole</th>
</tr>
<tr>
<td class="label">Parameter</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Bioavailability</td>
<td>~60%</td>
</tr>
<tr>
<td class="label">Protein binding</td>
<td>96% (mainly to albumin and lipoproteins)</td>
</tr>
<tr>
<td class="label">Metabolism</td>
<td>Hepatic, primarily CYP1A2</td>
</tr>
<tr>
<td class="label">Half-life</td>
<td>~12 hours (after repeated dosing)</td>
</tr>
<tr>
<td class="label">Excretion</td>
<td>Renal (90%, primarily as metabolites)</td>
</tr>
<tr>
<td class="label">Tmax</td>
<td>~1.5 hours</td>
</tr>
</table>

Introduction

...

Riluzole

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">riluzole</th>
</tr>
<tr>
<td class="label">Parameter</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Bioavailability</td>
<td>~60%</td>
</tr>
<tr>
<td class="label">Protein binding</td>
<td>96% (mainly to albumin and lipoproteins)</td>
</tr>
<tr>
<td class="label">Metabolism</td>
<td>Hepatic, primarily CYP1A2</td>
</tr>
<tr>
<td class="label">Half-life</td>
<td>~12 hours (after repeated dosing)</td>
</tr>
<tr>
<td class="label">Excretion</td>
<td>Renal (90%, primarily as metabolites)</td>
</tr>
<tr>
<td class="label">Tmax</td>
<td>~1.5 hours</td>
</tr>
</table>

Introduction

Riluzole is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

Riluzole (brand names: Rilutek, Tiglutik, Exservan) is a benzothiazole-class neuroprotective drug and the first medication approved by the United [@wikipedia2024]
States Food and Drug Administration (FDA) for the treatment of [amyotrophic lateral sclerosis (ALS)](/diseases/als). Approved in December 1995 in the US and in 1996 [@bhatt1998]
by the European Medicines Agency (EMA), riluzole remains one of only two FDA-approved disease-modifying therapies for ALS, alongside [@bensimon1994]
[edaravone](/therapeutics/edaravone) [@livertox2020] [@wikipedia2024]. The drug's primary [@andrews2020]
mechanism involves modulation of glutamatergic neurotransmission, specifically by inhibiting [glutamate](/entities/glutamate) release and blocking voltage-gated sodium [@bellingham2011]
channels on damaged [neurons](/entities/neurons) [@bhatt1998]. [@drugscom2024]

Riluzole was originally developed by Rhône-Poulenc (now Sanofi) and was first studied as an anticonvulsant before its neuroprotective properties were [@lacomblez1996]
recognized. The drug provides a modest but statistically significant survival benefit in ALS, extending median survival by approximately 2–3 months in [@mayo2024]
clinical trials, though real-world evidence suggests the benefit may be considerably larger [@bensimon1994] [@bhatt2024]
[@andrews2020]. [@grant2010]
Despite its modest efficacy, riluzole represented a landmark achievement as the first drug to demonstrate any effect on the course of a [Motor Neuron Disease](/diseases/motor-neuron-disease) and remains a cornerstone of ALS treatment worldwide. [@miller2012]

Mechanism of Action

Glutamate Release Inhibition

The precise mechanism of action of riluzole in ALS is not fully elucidated, but extensive preclinical and clinical evidence points to a primary role
in modulating [excitotoxicity](/entities/excitotoxicity)—the pathological overactivation of glutamate receptors that contributes to neuronal death in ALS and other
neurodegenerative conditions [@bhatt1998] [@bellingham2011].

Riluzole inhibits presynaptic glutamate release through multiple complementary mechanisms:

Inactivation of voltage-gated sodium channels: Riluzole preferentially blocks tetrodotoxin (TTX)-sensitive sodium channels in their inactivated state, reducing sustained repetitive firing of [neurons](/entities/neurons). This property is particularly relevant in diseased motor [neurons](/entities/neurons), which may exhibit aberrant hyperexcitability [@bhatt1998]

Enhancement of glutamate uptake: Riluzole stimulates the reuptake of glutamate from the synaptic cleft by activating glutamate transporters (particularly EAAT2/GLT-1) on [astrocytes](/cell-types/astrocytes), accelerating clearance and reducing extracellular glutamate concentrations [@bellingham2011]

Direct inhibition of glutamate release: Beyond its effects on sodium channels, riluzole appears to directly inhibit the presynaptic machinery for glutamate vesicle fusion and release [@bhatt1998]

Postsynaptic Receptor Modulation

In addition to its presynaptic effects, riluzole has been shown to interact with several postsynaptic targets:

• [NMDA receptor](/entities/nmda-receptor)] receptor] receptor] inhibition: Riluzole blocks [NMDA receptor](/entities/nmda-receptor)] receptor] receptor-mediated currents, reducing calcium influx through these ionotropic glutamate receptors [@bellingham2011]
• Kainate receptor inhibition: The drug also inhibits signaling through kainate-type glutamate receptors
• [GABA](/entities/gaba)_A receptor potentiation: Riluzole allosterically enhances GABA_A receptor function, potentially contributing to its neuroprotective effects through augmentation of inhibitory neurotransmission [@bellingham2011]

Neuroprotective Effects

Beyond glutamate modulation, riluzole exerts additional neuroprotective effects:

• Calcium channel modulation: The drug inhibits certain voltage-gated calcium channels, reducing calcium influx into [neurons](/entities/neurons)
• Potassium channel activation: Riluzole activates two-pore domain potassium channels (TREK-1), promoting neuronal hyperpolarization and reducing excitability
• Anti-inflammatory properties: Preclinical studies suggest riluzole may modulate [neuroinflammation](/mechanisms/neuroinflammation) by influencing [microglial/cell-types/[microglia](/cell-types/microglia)/entities/[microglia](/cell-types/microglia) activation states [link](https://pubmed.ncbi.nlm.nih.gov/20236142/)

Pharmacology

Pharmacokinetics

Riluzole is well absorbed after oral administration, with a bioavailability of approximately 60% due to first-pass hepatic metabolism. Key pharmacokinetic parameters include [@livertox2020]:

Metabolism

Riluzole undergoes extensive hepatic metabolism, primarily via cytochrome P450 1A2 (CYP1A2). The main metabolic pathway involves N-hydroxylation to form the primary metabolite N-hydroxyriluzole, followed by glucuronidation to form O- and N-glucuronides that are eliminated in the urine [@livertox2020]. CYP1A2 inducers (e.g., smoking, omeprazole, rifampicin) can accelerate riluzole metabolism, while CYP1A2 inhibitors (e.g., fluvoxamine, ciprofloxacin) can increase drug levels.

Dosing

The recommended dose is 50 mg taken orally twice daily (100 mg/day total), at least one hour before or two hours after meals to optimize absorption. Riluzole is available in several formulations [@drugscom2024]:

• Rilutek: 50 mg film-coated tablets
• Tiglutik: 50 mg/10 mL oral suspension (thickened, for patients with dysphagia)
• Exservan: 50 mg oral film (dissolves on the tongue, for patients unable to swallow tablets)

Clinical Trials

Pivotal Trial (Bensimon et al., 1994)

The first randomized controlled trial of riluzole in ALS was published in the New England Journal of Medicine in 1994. [This multicenter study
enrolled 155 patients and demonstrated that riluzole 100 mg/day significantly improved survival at 12 months compared with placebo (74% vs. 58%, p =
0.014). The survival benefit was most pronounced in patients with bulbar-onset ALS [@bensimon1994].

Confirmatory Trial (Lacomblez et al., 1996)

A larger confirmatory dose-ranging trial enrolled 959 patients across three doses (50, 100, and 200 mg/day) versus placebo. The study confirmed that riluzole 100 mg/day provided a statistically significant survival benefit, with a median survival prolongation of approximately 2–3 months. Higher doses (200 mg/day) showed no additional efficacy but increased toxicity [@lacomblez1996].

Real-World Evidence

Population-based studies have suggested that the real-world survival benefit of riluzole may exceed that observed in clinical trials. A 2020
systematic review of 8 real-world studies found that median survival for riluzole-treated patients was 6–19 months longer than for untreated patients
(p < 0.05), though these observational findings are subject to selection bias and confounding [@andrews2020].

Safety Profile

Hepatotoxicity

The most clinically significant adverse effect of riluzole is hepatotoxicity. Elevations in serum alanine aminotransferase (ALT) greater than three times the upper limit of normal occur in approximately 10–15% of patients, typically within the first three months of therapy [@livertox2020]. Current guidelines recommend:

• Baseline liver function tests before initiation
• Monthly ALT monitoring for the first 3 months
• Quarterly monitoring for the remainder of the first year
• Periodic monitoring thereafter
• Discontinuation if ALT exceeds 5× upper limit of normal or if clinical jaundice develops

Cases of clinically apparent liver injury with jaundice are rare (estimated at fewer than 1 in 1,000 patients), and fatal hepatotoxicity has been reported only in isolated cases [@livertox2020].

Common Adverse Effects

Other frequently reported adverse effects include [@mayo2024]:

• Asthenia/fatigue (18%)
• Nausea (15%)
• Dizziness (4%)
• Diarrhea (4%)
• Abdominal pain (3%)
• Paresthesia (2%)

Hematological Effects

Riluzole can cause neutropenia (low neutrophil count), with cases of severe neutropenia (<500 cells/mm³) reported rarely. Complete blood count monitoring is recommended, particularly during febrile illness [@mayo2024].

Interstitial Lung Disease

Rare cases of interstitial lung disease have been reported in patients receiving riluzole. Patients should be monitored for respiratory symptoms, and the drug should be discontinued if interstitial lung disease is suspected.

Investigational Uses

Neurodegenerative Diseases

Given its neuroprotective properties, riluzole has been investigated in several other neurodegenerative conditions:

• [Alzheimer's disease](/diseases/alzheimers-disease): A Phase 2 trial found that riluzole reduced the rate of hippocampal atrophy and preserved markers of synaptic integrity in patients with mild Alzheimer's Disease [@bhatt2024]
• [Huntington's disease](/mechanisms/huntington-pathway): Early-phase trials showed some evidence of reduced chorea, but no Phase 3 trial has been conducted
• [Spinocerebellar Ataxia](/diseases/spinocerebellar-ataxia): A randomized trial demonstrated modest improvement in ataxia scores with riluzole treatment
• [multiple sclerosis](/diseases/multiple-sclerosis): Investigated for neuroprotective effects in progressive MS

Psychiatric Disorders

Riluzole's glutamate-modulating properties have attracted interest for treatment of psychiatric conditions including [@grant2010]:

• Treatment-resistant depression
• Obsessive-compulsive disorder (OCD)
• Generalized anxiety disorder
• Bipolar disorder

Preliminary evidence suggests efficacy in treatment-resistant mood disorders, where glutamatergic dysfunction has been implicated in pathophysiology.

See Also

• [Neurodegenerative Drug Development Pipeline](/clinical-trials/drug-pipeline)

Background

The study of Riluzole has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
• [Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
• [Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

References

Unknown, LiverTox. (2020). Riluzole. In LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. NCBI Bookshelf. [NBK548919 (2020)

Unknown, Wikipedia contributors. (2024). Riluzole. In Wikipedia, The Free Encyclopedia. [Wikipedia (2024)

[Bhatt, A., et al., (1998). The pharmacology and mechanism of action of riluzole. Neurology, 47(6 Suppl 4), S233–S236. [PubMed 8959995 (1998)](https://pubmed.ncbi.nlm.nih.gov/8959995/)

Unknown, Bensimon, G., Lacomblez, L., & Meininger, V. (1994). A controlled trial of riluzole in amyotrophic lateral sclerosis. New England Journal of Medicine, 330(9), 585–591. [NEJM (1994)

Andrews, J.A., et al., (2020). Real-world evidence of riluzole effectiveness in treating amyotrophic lateral sclerosis. Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 21(7-8), 509–518. [Taylor & Francis (2020)

[Unknown, Bellingham, M.C. (2011). A review of the neural mechanisms of action and clinical efficiency of riluzole in treating amyotrophic lateral sclerosis. CNS Neuroscience & Therapeutics, 17(1), 4–31. [PubMed 20236142 (2011)](https://pubmed.ncbi.nlm.nih.gov/20236142/)

Unknown, Drugs.com. (2024). Riluzole: Package Insert / Prescribing Information. [Drugs.com (2024)

Lacomblez, L., et al., (1996). Dose-ranging study of riluzole in amyotrophic lateral sclerosis. The Lancet, 347(9013), 1425–1431. [Neurology (1996)

Unknown, Mayo Clinic. (2024). Riluzole (oral route) - Side effects & dosage. [Mayo Clinic (2024)

Unknown, Bhatt, D.K. (2024). Riluzole. ALZFORUM Therapeutics Database. [ALZFORUM (2024)

Grant, P., et al., (2010). Review of the use of the glutamate antagonist riluzole in psychiatric disorders. Journal of Clinical Psychopharmacology, 30(2), 199–204. [PMC2958461 (2010)

[Miller, R.G., et al. (2012). Riluzole for amyotrophic lateral sclerosis (ALS)/Motor, Neuron Disease (MND). Cochrane Database of Systematic Reviews, (3), CD001447. [DOI (2012)](https://doi.org/10.1002/14651858.CD001447.pub3)