Riluzole Drug Information

Riluzole tablets, USP are indicated for the treatment of amyotrophic lateral sclerosis (ALS). Riluzole is indicated for the treatment of amyotrophic lateral sclerosis (ALS)

The recommended dosage for riluzole is 50 mg taken orally twice daily. Riluzole should be taken at least 1 hour before or 2 hours after a meal . Measure serum aminotransferases before and during treatment with riluzole. Recommended dosage: 50 mg twice daily, taken at least 1 hour before or 2 hours after a meal Measure serum aminotransferases before and during treatment

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions in Controlled Clinical Trials In the placebo-controlled clinical trials in patients with ALS (Study 1 and 2), a total of 313 patients received riluzole 50 mg twice daily . The most common adverse reactions in the riluzole group (in at least 5% of patients and more frequently than in the placebo group) were asthenia, nausea, dizziness, decreased lung function, and abdominal pain. The most common adverse reactions leading to discontinuation in the riluzole group were nausea, abdominal pain, constipation, and elevated ALT. There was no difference in rates of adverse reactions leading to discontinuation in females and males.

However, the incidence of dizziness was higher in females (11%) than in males (4%). The adverse reaction profile was similar in older and younger patients. There were insufficient data to determine if there were differences in the adverse reaction profile in different races. Table 1 lists adverse reactions that occurred in at least 2% of riluzole-treated patients (50 mg twice daily) in pooled Study 1 and 2, and at a higher rate than placebo.

Table 1. Adverse Reactions in Pooled Placebo-Controlled Trials (Studies 1 and 2) in Patients with ALS Riluzole Tablets 50 mg twice daily (N=313) Placebo (N=320) Asthenia 19% 12% Nausea 16% 11% Decreased lung function 10% 9% Hypertension 5% 4% Abdominal pain 5% 4% Vomiting 4% 2% Arthralgia 4% 3% Dizziness 4% 3% Dry mouth 4% 3% Insomnia 4% 3% Pruritus 4% 3% Tachycardia 3% 1% Flatulence 3% 2% Increased cough 3% 2% Peripheral edema 3% 2% Urinary Tract Infection 3% 2% Circumoral paresthesia 2% 0% Somnolence 2% 1% Vertigo 2% 1% Eczema 2% 1%

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of riluzole. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Acute hepatitis and icteric toxic hepatitis Renal tubular impairment Pancreatitis

Agents that may Increase Riluzole Blood Concentrations

CYP1A2 inhibitors Coadministration of riluzole (a CYP1A substrate) with CYP1A2 inhibitors was not evaluated in a clinical trial; however, in vitro findings suggest an increase in riluzole exposure is likely. The concomitant use of strong or moderate CYP1A2 inhibitors (e.g., ciprofloxacin, enoxacin, fluvoxamine, methoxsalen, mexiletine, oral contraceptives, thiabendazole, vemurafenib, zileuton) with riluzole may increase the risk of riluzole-associated adverse reactions .

Agents that may Decrease Riluzole Plasma Concentrations

CYP1A2 inducers Coadministration of riluzole (a CYP1A substrate) with CYP1A2 inducers was not evaluated in a clinical trial; however, in vitro findings suggest a decrease in riluzole exposure is likely. Lower exposures may result in decreased efficacy .

Hepatotoxic Drugs Clinical trials in

ALS patients excluded patients on concomitant medications which were potentially hepatotoxic (e.g., allopurinol, methyldopa, sulfasalazine). Riluzole-treated patients who take other hepatotoxic drugs may be at an increased risk for hepatotoxicity .

Pregnancy Risk Summary There are no studies of riluzole 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 2 to 4% and 15 to 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 . Based on these results, women should be advised of a possible risk to the fetus associated with use of riluzole during pregnancy. Data 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/m 2 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/m 2 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/m 2 basis.

Pediatric Use Safety and effectiveness of riluzole in pediatric patients have not been established.

Riluzole tablets are contraindicated in patients with a history of severe hypersensitivity reactions to riluzole or to any of its components (anaphylaxis has occurred) . Patients with a history of severe hypersensitivity reactions to riluzole or to any of its components

Reported symptoms of overdose following ingestion of riluzole ranging from 1.5 to 3 grams (30 to 60 times the recommended dose) included acute toxic encephalopathy, coma, drowsiness, memory loss, and methemoglobinemia. No specific antidote for the treatment of riluzole overdose is available. For current information on the management of poisoning or overdosage, contact the National Poison Control Center at 1-800-222-1222 or www.poison.org.