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Included as part of the PRECAUTIONS section.


Hepatic Injury

Cases of drug-induced liver injury, some of which were fatal, have been reported in patients taking RILUTEK. Asymptomatic elevations of hepatic transaminases have also been reported, and in some patients have recurred upon rechallenge with RILUTEK.

In clinical studies, the incidence of elevations in hepatic transaminases was greater in RILUTEK-treated patients than placebo-treated patients. The incidence of elevations of ALT above 5 times the upper limit of normal (ULN) was 2% in RILUTEK-treated patients. Maximum increases in ALT occurred within 3 months after starting RILUTEK. About 50% and 8% of RILUTEK-treated patients in pooled Studies 1 and 2, had at least one elevated ALT level above ULN and above 3 times ULN, respectively [see Clinical Studies].

Monitor patients for signs and symptoms of hepatic injury, every month for the first 3 months of treatment, and periodically thereafter. The use of RILUTEK is not recommended if patients develop hepatic transaminases levels greater than 5 times the ULN. Discontinue RILUTEK if there is evidence of liver dysfunction (e.g., elevated bilirubin).


Cases of severe neutropenia (absolute neutrophil count less than 500 per mm³ ) within the first 2 months of RILUTEK treatment have been reported. Advise patients to report febrile illnesses.

Interstitial Lung Disease

Interstitial lung disease, including hypersensitivity pneumonitis, has occurred in patients taking RILUTEK. Discontinue RILUTEK immediately if interstitial lung disease develops.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility


Riluzole was not carcinogenic in mice or rats when administered for 2 years at daily oral doses up to 20 and 10 mg/kg/day, respectively, which are approximately equal to the recommended human daily dose (RHDD, 100 mg) on a mg/m² basis.


Riluzole was negative in in vitro (bacterial reverse mutation (Ames), mouse lymphoma tk, chromosomal aberration assay in human lymphocytes), and in vivo (rat cytogenetic and mouse micronucleus) assays.

N-hydroxyriluzole, the major active metabolite of riluzole, was positive for clastogenicity in the in vitro mouse lymphoma tk assay and in the in vitro micronucleus assay using the same mouse lymphoma cell line. N-hydroxyriluzole was negative in the HPRT gene mutation assay, the Ames assay (with and without rat or hamster S9), the in vitro chromosomal aberration assay in human lymphocytes, and the in vivo mouse micronucleus assay.

Impairment Of Fertility

When riluzole (3, 8, or 15 mg/kg) was administered orally to male and female rats prior to and during mating and continuing in females throughout gestation and lactation, fertility indices were decreased and embryolethality was increased at the high dose. This dose was also associated with maternal toxicity. The mid dose, a no-effect dose for effects on fertility and early embryonic development, is approximately equal to the RHDD on a mg/m² basis.

Use In Specific Populations


Risk Summary

There are no studies of RILUTEK in pregnant women, and case reports have been inadequate to inform the drug-associated risk. The background risk for major birth defects and miscarriage in patients with amyotrophic lateral sclerosis is unknown. In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 24% and 15-20%, respectively.

In studies in which riluzole was administered orally to pregnant animals, developmental toxicity (decreased embryofetal/offspring viability, growth, and functional development) was observed at clinically relevant doses [see Data]. Based on these results, women should be advised of a possible risk to the fetus associated with use of RILUTEK during pregnancy.


Animal Data

Oral administration of riluzole (3, 9, or 27 mg/kg/day) to pregnant rats during the period of organogenesis resulted in decreases in fetal growth (body weight and length) at the high dose. The mid dose, a no-effect dose for embryofetal developmental toxicity, is approximately equal to the recommended human daily dose (RHDD, 100 mg) on a mg/m² basis. When riluzole was administered orally (3, 10, or 60 mg/kg/day) to pregnant rabbits during the period of organogenesis, embryofetal mortality was increased at the high dose and fetal body weight was decreased and morphological variations increased at all but the lowest dose tested. The no-effect dose (3 mg/kg/day) for embryofetal developmental toxicity is less than the RHDD on a mg/m² basis. Maternal toxicity was observed at the highest dose tested in rat and rabbit.

When riluzole was orally administered (3, 8, or 15 mg/kg/day) to male and female rats prior to and during mating and to female rats throughout gestation and lactation, increased embryofetal mortality and decreased postnatal offspring viability, growth, and functional development were observed at the high dose. The mid dose, a no-effect dose for pre-and postnatal developmental toxicity, is approximately equal to the RHDD on a mg/m² basis.


Risk Summary

It is not known if riluzole is excreted in human milk. Riluzole or its metabolites have been detected in milk of lactating rat. Women should be advised that many drugs are excreted in human milk and that the potential for serious adverse reactions in nursing infants from RILUTEK is unknown.

Females And Males Of Reproductive Potential

In rats, oral administration of riluzole resulted in decreased fertility indices and increases in embryolethality [see Nonclinical Toxicology].

Pediatric Use

Safety and effectiveness of RILUTEK in pediatric patients have not been established.

Geriatric Use

In clinical studies of RILUTEK, 30% of patients were 65 years and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Hepatic Impairment

Patients with mild [Child-Pugh's (CP) score A] or moderate (CP score B) hepatic impairment had increases in AUC compared to patients with normal hepatic function. Thus, patients with mild or moderate hepatic impairment may be at increased of adverse reactions. The impact of severe hepatic impairment on riluzole exposure is unknown.

Use of RILUTEK is not recommended in patients with baseline elevation of elevations of serum aminotransferases greater than 5 times upper limit of normal or evidence of liver dysfunction (e.g., elevated bilirubin) [CLINICAL PHARMACOLOGY].

Japanese Patients

Japanese patients are more likely to have higher riluzole concentrations. Consequently, the risk of adverse reactions may be greater in Japanese patients [see CLINICAL PHARMACOLOGY].

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 6/7/2016


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