Rilutek (Riluzole)
Glutamate release inhibitor for the treatment of amyotrophic lateral sclerosis (ALS)
Quick Facts About Rilutek (Riluzole)
Key Takeaways About Rilutek
- First approved ALS treatment: Rilutek (riluzole) was the first drug approved specifically for ALS and remains a cornerstone of ALS therapy worldwide
- Extends survival: Clinical trials have shown riluzole extends survival by approximately 2–3 months and may delay the need for tracheostomy or mechanical ventilation
- Liver monitoring is essential: Regular blood tests to check liver function (transaminases) are required, especially during the first year of treatment
- Simple dosing: One 50 mg tablet taken twice daily, every 12 hours, at the same times each day
- Tell your doctor about fever: Riluzole can lower white blood cell counts; report any unexplained fever immediately as it may indicate neutropenia
What Is Rilutek and What Is It Used For?
Rilutek (riluzole) is a prescription medicine used to treat amyotrophic lateral sclerosis (ALS), also known as motor neuron disease or Lou Gehrig's disease. It works by reducing the release of glutamate in the brain and spinal cord, helping to slow the destruction of motor neurons that control voluntary movement.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects the motor neurons – the nerve cells responsible for sending instructions to the muscles. As these nerve cells deteriorate and die, patients gradually lose the ability to move, speak, eat, and eventually breathe. ALS affects approximately 2–5 per 100,000 people worldwide, with most cases occurring between the ages of 40 and 70.
The active substance in Rilutek is riluzole, a benzothiazole compound that acts on the nervous system. Riluzole was the first drug approved specifically for ALS, initially receiving approval from the FDA in 1995 and subsequently from the European Medicines Agency (EMA). It remains one of only a few pharmacological treatments available for this devastating condition.
The primary mechanism of action involves inhibiting the release of glutamate, an excitatory neurotransmitter. In ALS, excessive glutamate activity is believed to cause excitotoxic damage to motor neurons. By blocking glutamate release from presynaptic nerve terminals and interfering with voltage-dependent sodium channels, riluzole helps protect motor neurons from this type of damage. Additionally, riluzole may have neuroprotective effects through other pathways, including interference with intracellular signaling that occurs after glutamate binds to its receptors.
It is important to understand that riluzole does not cure ALS and does not reverse damage that has already occurred to motor neurons. However, landmark clinical trials – notably the two pivotal randomized controlled trials published in the 1990s – demonstrated that riluzole can extend survival by approximately 2–3 months and delay the need for mechanical ventilation. The benefit appears to be greatest when treatment is initiated early in the disease course, making timely diagnosis and treatment initiation particularly important.
Glutamate is the most abundant excitatory neurotransmitter in the central nervous system and plays essential roles in normal brain function, including learning and memory. However, when glutamate accumulates to excessive levels – as appears to occur in ALS – it overstimulates neurons, leading to a cascade of events that ultimately causes cell death. This process, known as excitotoxicity, is considered one of the key pathological mechanisms in ALS. By reducing glutamate release, riluzole helps mitigate this destructive process.
What Should You Know Before Taking Rilutek?
Before starting Rilutek, your doctor must evaluate your liver function, current medications, and overall health status. Riluzole is contraindicated in patients with liver disease or elevated transaminases, during pregnancy and breastfeeding, and in those with known hypersensitivity to riluzole or its excipients.
Taking any medication requires careful consideration of potential risks and benefits. Because riluzole is metabolized primarily by the liver and can cause hepatotoxicity, a thorough medical evaluation is necessary before starting treatment. Your prescribing physician will consider your complete medical history, current medications, and laboratory results to determine whether Rilutek is appropriate for you.
Contraindications
You should not take Rilutek if any of the following apply to you:
- Allergy to riluzole or any other ingredient: If you have ever had a hypersensitivity reaction to riluzole or any of the excipients listed in the ingredients section, you must not take this medicine
- Liver disease: If you have an existing liver condition or if blood tests show elevated levels of liver enzymes (transaminases), riluzole should not be used, as it can worsen liver function
- Pregnancy or breastfeeding: Riluzole is contraindicated during pregnancy and in women who are breastfeeding due to potential risks to the developing fetus or nursing infant
Warnings and Precautions
Speak with your doctor before taking Rilutek if any of the following situations apply to you:
- Liver problems: If you notice yellowing of the skin or whites of the eyes (jaundice), widespread itching, nausea, or vomiting, contact your doctor immediately as these may be signs of liver damage (hepatitis). Your doctor will perform regular blood tests to monitor liver function throughout treatment
- Kidney impairment: If your kidneys are not working properly, inform your doctor as dose adjustments or closer monitoring may be necessary
- Unexplained fever: Report any fever to your doctor promptly. Riluzole can reduce the number of white blood cells (neutropenia), which can increase your risk of infection. A blood test may be needed to check your white blood cell count
Your doctor should check your liver enzymes (ALT/AST) before starting treatment, monthly for the first 3 months, every 3 months for the rest of the first year, and periodically thereafter. If levels rise above 5 times the upper limit of normal, treatment should be stopped. Tell your doctor immediately if you develop signs of liver problems such as jaundice, unexplained nausea, or vomiting.
Pregnancy and Breastfeeding
You must not take Rilutek if you are pregnant, think you may be pregnant, or are breastfeeding. There is insufficient data on the use of riluzole in pregnant women, and animal studies have shown potential reproductive toxicity. If you are a woman of childbearing potential, discuss appropriate contraception with your doctor before starting treatment.
It is not known whether riluzole passes into breast milk. Given the potential risks to the nursing infant, breastfeeding should be discontinued before starting riluzole therapy. If you are planning to become pregnant or discover that you are pregnant during treatment, contact your doctor immediately to discuss the best course of action.
Children and Adolescents
Rilutek is not recommended for patients under 18 years of age. There is insufficient clinical data on the safety and efficacy of riluzole in children and adolescents with ALS or other conditions. ALS is extremely rare in this age group, and alternative diagnoses should be carefully considered.
Driving and Operating Machinery
You may drive and use machinery while taking Rilutek, provided you do not experience dizziness or light-headedness. These are known side effects of riluzole, and if they occur, you should avoid driving or operating dangerous machinery until the symptoms resolve. It is also important to note that ALS itself can impair motor function and may affect your ability to drive safely, regardless of medication.
How Does Rilutek Interact with Other Drugs?
Riluzole is primarily metabolized by the liver enzyme CYP1A2. Drugs that inhibit CYP1A2 (such as fluvoxamine and ciprofloxacin) can significantly increase riluzole blood levels, while CYP1A2 inducers (such as rifampicin and cigarette smoking) can decrease its effectiveness. Always inform your doctor about all medicines you are taking.
Drug interactions are an important consideration with any medication. Riluzole is extensively metabolized in the liver, primarily by the cytochrome P450 enzyme CYP1A2, with minor contributions from CYP3A4 and other enzymes. Because of this metabolic pathway, several classes of drugs can affect riluzole blood concentrations, potentially increasing the risk of side effects or reducing the drug's effectiveness.
It is essential to tell your doctor or pharmacist about all medicines you are currently taking, have recently taken, or might take. This includes prescription drugs, over-the-counter medications, herbal supplements, and vitamins. Your doctor can then assess whether any adjustments to your treatment plan are needed.
| Interacting Drug | Effect | Severity | Recommendation |
|---|---|---|---|
| Fluvoxamine (CYP1A2 inhibitor) | Increases riluzole levels up to 5-fold | Major | Avoid combination; use alternative antidepressant |
| Ciprofloxacin (CYP1A2 inhibitor) | Significantly increases riluzole levels | Major | Use alternative antibiotic if possible |
| Rifampicin (CYP1A2 inducer) | Decreases riluzole levels; may reduce efficacy | Moderate | Monitor closely; dose adjustment may be needed |
| Omeprazole (CYP1A2 inducer) | May decrease riluzole levels | Moderate | Consider alternative proton pump inhibitor |
| Theophylline (CYP1A2 substrate) | Competitive metabolism; may alter levels of both drugs | Moderate | Monitor theophylline levels closely |
| Hepatotoxic drugs | Increased risk of liver damage | Major | Avoid if possible; increase liver monitoring frequency |
| Cigarette smoking | Induces CYP1A2; may decrease riluzole levels | Moderate | Inform doctor of smoking status; dose may need adjustment |
Major Interactions
The most clinically significant interaction is with fluvoxamine, a potent CYP1A2 inhibitor used as an antidepressant. Co-administration can increase riluzole plasma concentrations by up to 5-fold, dramatically increasing the risk of hepatotoxicity and other adverse effects. This combination should be avoided entirely. Similarly, ciprofloxacin, a commonly prescribed fluoroquinolone antibiotic, is a strong CYP1A2 inhibitor and can substantially raise riluzole levels.
Other potent CYP1A2 inhibitors to be aware of include enoxacin, ticlopidine, and some herbal preparations. Concomitant use of other hepatotoxic medications – such as certain antibiotics, antifungals, anticonvulsants, or high-dose acetaminophen (paracetamol) – can compound the liver risks associated with riluzole and should be approached with caution.
Minor Interactions
Mild CYP1A2 inducers and inhibitors may have modest effects on riluzole blood levels that are generally not clinically significant but should still be considered. Caffeine is a CYP1A2 substrate, and while normal dietary caffeine intake is unlikely to cause problems, very high caffeine consumption could theoretically compete with riluzole metabolism. Charcoal-grilled foods contain polycyclic aromatic hydrocarbons that induce CYP1A2 and may slightly reduce riluzole levels if consumed regularly in large quantities.
What Is the Correct Dosage of Rilutek?
The recommended dose of Rilutek is one 50 mg tablet twice daily (total 100 mg/day), taken every 12 hours at the same times each day, such as morning and evening. Swallow the tablets whole with water. Do not adjust the dose without consulting your doctor.
Always take Rilutek exactly as your doctor has prescribed. If you are unsure about any aspect of your dosing, consult your doctor or pharmacist. The standard dosing regimen is straightforward and does not typically require adjustment based on body weight, age, or the severity of ALS symptoms. Consistency in timing is important to maintain stable blood levels of the drug throughout the day.
Adults
Standard Adult Dosage
50 mg (one tablet) twice daily, taken approximately every 12 hours. The total daily dose is 100 mg. Take the tablets at consistent times each day – for example, one tablet in the morning and one in the evening. Swallow the tablet whole with water. Riluzole can be taken with or without food, though taking it at the same times helps ensure consistent drug levels.
Clinical trials evaluated various doses of riluzole, ranging from 50 mg to 200 mg daily. The 100 mg daily dose (50 mg twice daily) was established as the optimal balance between efficacy and tolerability. Higher doses did not provide additional survival benefit but were associated with a significantly increased risk of adverse effects, particularly liver toxicity. Therefore, the standard 100 mg/day dose should not be exceeded.
Children
Pediatric Use
Not recommended. Rilutek is not approved for use in patients under 18 years of age. Insufficient clinical data exist regarding the safety and efficacy of riluzole in pediatric populations. ALS is exceedingly rare in children, and use in this population should only be considered under exceptional circumstances with specialist supervision.
Elderly
Elderly Patients
No dose adjustment is generally required for elderly patients. However, because older individuals are more likely to have reduced hepatic and renal function, closer monitoring – particularly of liver enzymes – may be prudent. Your doctor will determine the most appropriate monitoring schedule based on your individual health status.
Missed Dose
If you forget to take a dose of Rilutek, skip the missed dose and take the next dose at your regular scheduled time. Do not take a double dose to compensate for the forgotten tablet. Taking two doses too close together can increase the risk of side effects, particularly nausea and elevated liver enzymes. If you frequently forget doses, consider setting a daily alarm or using a pill organizer to help you remember.
Overdose
If you have taken more tablets than prescribed, contact your doctor or go to the nearest emergency department immediately. Symptoms of overdose may include nausea, vomiting, drowsiness, and potentially serious liver damage. There is no specific antidote for riluzole overdose; treatment is supportive and symptomatic. Bring the medication packaging with you to help healthcare providers understand what you have taken.
| Patient Group | Dose | Frequency | Notes |
|---|---|---|---|
| Adults | 50 mg | Twice daily (every 12 hours) | Total daily dose: 100 mg |
| Elderly | 50 mg | Twice daily (every 12 hours) | No dose adjustment; monitor liver function closely |
| Children (<18 years) | Not recommended | N/A | Insufficient safety and efficacy data |
| Renal impairment | 50 mg | Twice daily | Use with caution; monitor closely |
| Hepatic impairment | Contraindicated | N/A | Do not use in liver disease or elevated ALT/AST |
What Are the Side Effects of Rilutek?
The most common side effects of Rilutek include tiredness (asthenia), nausea, and elevated liver enzymes. More serious but less common side effects include hepatitis (liver inflammation), neutropenia (low white blood cells), and interstitial lung disease. Report any unexplained fever, jaundice, or breathing difficulties to your doctor immediately.
Like all medicines, Rilutek can cause side effects, although not everybody experiences them. Most side effects are mild to moderate and may improve as your body adjusts to the medication. However, some side effects can be serious and require immediate medical attention. Understanding what to watch for can help you work with your doctor to manage your treatment safely.
- Fever: Riluzole can lower your white blood cell count. Your doctor may need to check your blood to rule out neutropenia, which increases infection risk
- Yellowing of the skin or eyes (jaundice), whole-body itching, nausea, or vomiting: These may be signs of liver damage (hepatitis). Regular blood tests are essential to detect this early
- Cough or difficulty breathing: These may indicate interstitial lung disease, a rare but potentially serious complication
Very Common Side Effects
- Tiredness (asthenia/fatigue)
- Nausea
- Elevated blood levels of liver enzymes (transaminases)
Common Side Effects
- Dizziness
- Drowsiness (somnolence)
- Headache
- Tingling in the mouth (oral paraesthesia)
- Increased heart rate (tachycardia)
- Abdominal pain
- Vomiting
- Diarrhea
- Pain
Uncommon Side Effects
- Anemia (low red blood cell count)
- Allergic reactions (hypersensitivity)
- Pancreatitis (inflammation of the pancreas)
Reported Side Effects
- Skin rash
- Hepatitis (liver inflammation)
- Interstitial lung disease
- Neutropenia (low white blood cell count)
Understanding Liver-Related Side Effects
Elevated transaminases (liver enzymes) are one of the most common side effects of riluzole and can occur in more than 10% of patients. In most cases, these elevations are mild and asymptomatic, resolving either spontaneously or after dose reduction. However, in some patients, the elevation can be significant enough to indicate liver damage (hepatotoxicity).
The recommended monitoring schedule – monthly for the first three months, then every three months during the first year – is designed to detect liver problems early, before they become clinically significant. If your ALT levels rise above 5 times the upper limit of normal, your doctor will likely discontinue riluzole. Patients with pre-existing liver conditions or those taking other hepatotoxic medications are at higher risk and should be monitored more frequently.
Managing Common Side Effects
Nausea is one of the most frequently reported side effects and is usually mild. Taking riluzole with food may help reduce nausea, although this is not strictly required. If nausea is persistent and bothersome, your doctor may recommend anti-nausea medication. Fatigue is another very common effect and can sometimes be difficult to distinguish from the fatigue caused by ALS itself. Maintaining a regular sleep schedule and gentle physical activity, as tolerated, may help manage this symptom.
Dizziness and drowsiness can affect your ability to drive or operate machinery safely. These effects are usually transient, occurring most commonly during the first few weeks of treatment. If they persist, discuss this with your doctor. Oral tingling (paraesthesia) is a distinctive side effect of riluzole and is generally harmless and temporary, though it may be uncomfortable.
If you experience any side effects – whether listed here or not – talk to your doctor, pharmacist, or nurse. You can also report side effects directly to your national medicines agency (for example, the FDA MedWatch program in the United States, the Yellow Card Scheme in the United Kingdom, or the EMA in Europe). By reporting side effects, you help provide important safety information about medicines.
How Should You Store Rilutek?
Store Rilutek at room temperature, out of the reach and sight of children. No special storage conditions are required. Do not use after the expiry date printed on the packaging. Do not dispose of medicines via wastewater or household waste – ask your pharmacist for proper disposal methods.
Proper storage of medications is important to ensure they remain effective and safe to use. Rilutek does not require any special storage conditions – it should be kept at normal room temperature, away from excessive heat, moisture, and direct sunlight. Keep the tablets in their original blister packaging until you are ready to take them.
Always check the expiry date on the carton and blister pack before taking a tablet. The expiry date refers to the last day of the month indicated. Do not use Rilutek after this date, as the drug's potency and safety cannot be guaranteed beyond the expiration period.
Keep this medicine out of the sight and reach of children. If a child accidentally ingests riluzole tablets, seek medical attention immediately. Unused or expired medicines should not be thrown in regular household waste or flushed down the toilet. Instead, return them to your pharmacy for safe disposal. These measures help protect the environment from pharmaceutical contamination.
What Does Rilutek Contain?
Each Rilutek tablet contains 50 mg of the active substance riluzole. The inactive ingredients include calcium hydrogen phosphate (anhydrous), microcrystalline cellulose, anhydrous colloidal silica, magnesium stearate, and croscarmellose sodium in the tablet core, with hypromellose, macrogol 6000, and titanium dioxide (E171) in the film coating.
Understanding the composition of your medicine is important, particularly if you have known allergies or sensitivities to specific excipients. The active ingredient, riluzole, is a benzothiazole compound with the chemical name 2-amino-6-(trifluoromethoxy)benzothiazole. Each film-coated tablet contains exactly 50 mg of riluzole.
Active Ingredient
Riluzole 50 mg – a glutamate release inhibitor with neuroprotective properties. Riluzole has a molecular weight of 234.2 g/mol and is practically insoluble in water but soluble in dimethylformamide and methanol.
Inactive Ingredients (Excipients)
The inactive ingredients serve various pharmaceutical functions:
- Tablet core: Calcium hydrogen phosphate (anhydrous) – filler/diluent; microcrystalline cellulose – binder; anhydrous colloidal silica – glidant; magnesium stearate – lubricant; croscarmellose sodium – disintegrant
- Film coating: Hypromellose – film-forming agent; macrogol 6000 (polyethylene glycol) – plasticizer; titanium dioxide (E171) – opacifier/whitening agent
Appearance and Packaging
Rilutek tablets are film-coated, capsule-shaped, and white. Each tablet is engraved with "RPR 202" on one side. The medicine is supplied in packs of 56 tablets in blister strips.
Rilutek contains less than 1 mmol (23 mg) of sodium per tablet, which means it is essentially sodium-free. This is relevant for patients on sodium-restricted diets, such as those with heart failure or kidney disease.
Frequently Asked Questions About Rilutek
Rilutek (riluzole) is used to treat amyotrophic lateral sclerosis (ALS), also known as motor neuron disease or Lou Gehrig's disease. It is the first drug specifically approved for ALS and works by reducing the release of glutamate, a chemical messenger in the brain that can damage nerve cells when present in excess. Rilutek has been shown to extend survival by approximately 2–3 months and may delay the need for mechanical ventilation. It does not cure ALS but helps slow disease progression.
Riluzole works primarily by inhibiting the release of glutamate from presynaptic nerve terminals in the central nervous system. In ALS, motor neurons are damaged partly due to excessive glutamate activity (a process called excitotoxicity). By reducing glutamate release and blocking voltage-dependent sodium channels, riluzole helps protect remaining motor neurons from further damage. It also interferes with intracellular signaling pathways that contribute to neuronal death.
Regular blood tests are necessary because riluzole can affect your liver function. Elevated liver enzymes (transaminases) are one of the most common side effects, occurring in more than 10% of patients. Your doctor will check your liver enzymes before starting treatment, monthly for the first 3 months, every 3 months during the rest of the first year, and periodically thereafter. Additionally, riluzole can sometimes lower your white blood cell count, so blood tests help detect this early. If significant liver enzyme elevations are detected, your doctor may need to stop the medication.
While there is no absolute prohibition against alcohol use with riluzole, it is generally advisable to limit or avoid alcohol consumption. Both riluzole and alcohol are metabolized by the liver, and combining them may increase the risk of hepatotoxicity (liver damage). Alcohol can also worsen common side effects such as dizziness, drowsiness, and nausea. Discuss your alcohol consumption with your doctor, who can provide personalized advice based on your liver function test results.
No, Rilutek cannot cure ALS. Currently, there is no cure for amyotrophic lateral sclerosis. Riluzole is a disease-modifying treatment that has been shown to slow disease progression and extend survival by approximately 2–3 months on average. The benefit appears greatest when treatment is started early in the disease course. Riluzole is most effective as part of a comprehensive management approach that includes physical therapy, occupational therapy, speech therapy, nutritional support, respiratory care, and multidisciplinary team care.
Difficulty swallowing (dysphagia) is a common symptom of ALS that can make taking tablets challenging. If you have trouble swallowing Rilutek tablets, talk to your doctor. In some countries, an oral suspension formulation of riluzole is available, which may be easier to swallow. Your doctor or pharmacist may also be able to advise on whether the tablets can be crushed or dissolved. Never modify your medication without consulting your healthcare team first, as this can affect how the drug is absorbed.
References
- Bensimon G, Lacomblez L, Meininger V. A controlled trial of riluzole in amyotrophic lateral sclerosis. New England Journal of Medicine. 1994;330(9):585-591. doi:10.1056/NEJM199403033300901
- Lacomblez L, Bensimon G, Leigh PN, et al. Dose-ranging study of riluzole in amyotrophic lateral sclerosis. The Lancet. 1996;347(9013):1425-1431. doi:10.1016/S0140-6736(96)91680-3
- Miller RG, Mitchell JD, Moore DH. Riluzole for amyotrophic lateral sclerosis (ALS)/motor neuron disease (MND). Cochrane Database of Systematic Reviews. 2012;(3):CD001447. doi:10.1002/14651858.CD001447.pub3
- European Medicines Agency (EMA). Rilutek – Summary of Product Characteristics. Last updated 2023.
- U.S. Food and Drug Administration (FDA). Rilutek (riluzole) – Prescribing Information. Revised 2023.
- National Institute for Health and Care Excellence (NICE). Motor neurone disease: assessment and management. NICE guideline [NG42]. Updated 2024.
- Andersen PM, Abrahams S, Borasio GD, et al. EFNS guidelines on the clinical management of amyotrophic lateral sclerosis (MALS). European Journal of Neurology. 2012;19(3):360-375.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List, 2023.
- Bellingham MC. A review of the neural mechanisms of action and clinical efficiency of riluzole in treating amyotrophic lateral sclerosis. CNS Neuroscience & Therapeutics. 2011;17(1):4-31.
- Andrews JA, Jackson CE, Heiman-Patterson TD, et al. Real-world evidence of riluzole effectiveness in treating amyotrophic lateral sclerosis. Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration. 2020;21(7-8):509-518.
Editorial Team
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iMedic Medical Editorial Team
Specialists in neurology and clinical pharmacology with extensive experience in neurodegenerative disease management and drug information.
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iMedic Medical Review Board
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This article was written based on official prescribing information from the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA), supplemented by peer-reviewed clinical trial data and international treatment guidelines. All content follows the GRADE evidence framework and is reviewed regularly to reflect the latest clinical evidence.
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