RILUTEK
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RILUTEK (RILUTEK).
Exact mechanism unknown. Reduces glutamate-mediated excitotoxicity via inhibition of glutamate release and postsynaptic glutamate receptor blockade.
| Metabolism | Hepatic via CYP1A2 (major) and glucuronidation to inactive metabolites. |
| Excretion | Primarily hepatic metabolism; 90% excreted in urine as metabolites (glucuronide and N-hydroxyriluzole) and 5% in feces. <1% unchanged in urine. |
| Half-life | Terminal half-life is 12 hours after repeated oral dosing (range 9-15 hours), increasing to ~20 hours in patients with mild hepatic impairment. Steady-state reached in 5 days. |
| Protein binding | 97% bound, primarily to albumin and lipoproteins. |
| Volume of Distribution | 3.4 L/kg (range 2.5-4.5 L/kg), indicating extensive tissue distribution. |
| Bioavailability | Approximately 60% after oral administration (range 30-90%), reduced by 45% with high-fat meals. |
| Onset of Action | Oral: Clinical effect on survival in ALS is observed after 18 months of continuous therapy; no immediate symptomatic effect. |
| Duration of Action | Duration is continuous with daily dosing; requires lifelong therapy for potential survival benefit. No acute duration defined. |
50 mg orally every 12 hours
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min; insufficient data for GFR <30 mL/min, use with caution. |
| Liver impairment | Contraindicated in Child-Pugh class B and C; no specific guidance for Child-Pugh class A, but monitor closely. |
| Pediatric use | Safety and efficacy not established; no standard pediatric dosing available. |
| Geriatric use | No specific dose adjustment; pharmacokinetics similar to younger adults, but monitor renal and hepatic function due to age-related changes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RILUTEK (RILUTEK).
| Breastfeeding | M/P ratio unknown. Excretion in human milk is likely given molecular weight (234.2 Da) and moderate lipophilicity (logP 1.5). Use caution; consider alternative feeding if maternal therapy required. |
| Teratogenic Risk | Pregnancy Category C. First trimester: Animal studies show delayed ossification and increased resorption at doses 2-4 times human exposure; human data insufficient to assess risk. Second trimester: No specific data due to low enrollment in trials; potential for fetal harm from maternal disease (ALS). Third trimester: Theoretical risk of fetal respiratory depression with maternal neuromuscular weakness. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to riluzole or any excipients, severe hepatic impairment (Child-Pugh C).
| Precautions | Hepatotoxicity (monitor ALT/AST), neutropenia (monitor ANC), interstitial lung disease, cough, dizziness. |
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| Fetal Monitoring | Monitor maternal liver function (ALT, AST every month for first 3 months, then periodically); assess fetal growth and amniotic fluid volume with ultrasound every 4-6 weeks; monitor for maternal respiratory function if bulbar involvement. |
| Fertility Effects | Animal studies: reduced fertility in males at high doses. Human data: limited; no known impact on female fertility. May affect sperm parameters due to oxidative stress modulation. |