Rilutek 50 mg

A high fat meal decreases absorption (see Action and Clinical Pharmacology, Pharmacokinetics, Absorption). RILUTEK tablets should be taken at least 1 hour before, or 2 hours after, a meal to avoid a food-related decrease in bioavailability (see Dosage and Administration).

Interactions with laboratory tests have not been established.

The clinical trials in ALS excluded patients on concomitant medications which were potentially hepatotoxic, (e.g., allopurinol, methyldopa, sulfasalazine). Accordingly, there is no information about the safety of administering RILUTEK in conjunction with such medications. If the practitioner chooses to prescribe such a combination, caution should be exercised.

RILUTEK is highly bound (96%) to plasma proteins, binding mainly to serum albumin and to lipoproteins. The effect of RILUTEK (up to 5 µg/mL) on warfarin (5 µg/mL) binding did not show any displacement of warfarin. Conversely, RILUTEK binding was unaffected by the addition of warfarin, digoxin, imipramine and quinine at high therapeutic concentrations.

CYP 1A2 is the principal isoenzyme involved in the initial oxidative metabolism of RILUTEK; potential interactions may occur when RILUTEK is given concurrently with other agents which are also metabolized primarily by CYP 1A2 (e.g. theophylline, caffeine and tacrine). Currently, it is not known whether RILUTEK has any potential for enzyme induction in humans.

Interactions with herbal products have not been established.

In vitro studies using human liver microsomal preparations suggest that CYP 1A2 is the principal isozyme involved in the initial oxidative metabolism of RILUTEK, and, therefore, potential interactions may occur when RILUTEK is given concurrently with agents that affect CYP 1A2 activity. Potential inhibitors of CYP 1A2 (e.g., caffeine, phenacetin, theophylline, amitriptyline, and quinolones) could decrease the rate of RILUTEK elimination, while inducers of CYP 1A2 (e.g., cigarette smoke, charcoal-broiled food, rifampicin, and omeprazole) could increase the rate of RILUTEK elimination.

There have been no clinical studies to evaluate the interaction of RILUTEK with other drugs. As CYP 1A2 is the principal isoenzyme involved in the initial oxidative metabolism of RILUTEK, it appears that CYP 1A2 inhibition or induction is the major source of potential drug interaction.

There have been no clinical studies to evaluate the interaction of RILUTEK with other drugs

As with all drugs, the potential for interaction by a variety of mechanisms is a possibility.

RILUTEK is contraindicated in patients who have hepatic disease or who have baseline transaminases greater than 3 times the ULN (upper limit of normal). Liver chemistries should be monitored in all patients on RILUTEK regularly for the first year of treatment, and periodically thereafter (see Contraindications, Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries; Action and Clinical Pharmacology, Special Populations and Conditions, Hepatic Insufficiency).

RILUTEK is not recommended for use in children, as the safety and efficacy of RILUTEK in any neurodegenerative disease occurring in children or adolescents have not been established.

RILUTEK tablets should be taken at least 1 hour before, or 2 hours after, a meal to avoid a food-related decrease in bioavailability.

Based on pharmacokinetic data from a dedicated PK study and from the efficacy trials, there are no special instructions for the use of RILUTEK in this population (see Action and Clinical Pharmacology, Special Populations and Conditions, Geriatrics).

The dose at which survival benefit is seen in clinical trials is 50 mg every 12 hours.

No evidence exists to define the duration of the benefit of continued RILUTEK use. Similarly, there is no evidence of additional benefit if RILUTEK is continued after tracheostomy is performed for ventilation.

RILUTEK is not recommended for use in patients with impaired renal function, as studies at repeated doses have not been conducted in this population (see Warnings and Precautions, Special Populations, Renal Insufficiency; Action and Clinical Pharmacology, Special Populations and Conditions, Renal Insufficiency).

If a dose of RILUTEK is missed, the next dose should be taken at the next scheduled time. Extra tablets should not be taken to make up for the missed dose.

cardioactive drug level increased.

blindness.

inappropriate antidiuretic hormone selection.

RILUTEK has been administered to 1713 individuals during all clinical trials, some of which were placebo-controlled (safety data from Study 401 are not included due to differences in data collection process). All reported adverse events are included below except those already listed in the previous tables, those too general to be informative, and those events where a drug cause was remote. For the placebo-controlled trials, events are included if the incidence rate for RILUTEK is numerically greater than the rate for placebo. It is important to emphasize that although the events reported occurred during treatment with RILUTEK, they were not necessarily caused by it.

Events are classified within body system categories and enumerated in order of decreasing frequency using the following definitions: common (≥1%), uncommon (≥0.1% and <1%); rare (≥0.01% and <0.1%), very rare <0.01%).

accidental overdose, extradural haematoma, post procedural haemorrhage.

alveolitis, alveolitis allergic, aspiration, choking, cough, dyspnoea, eosinophilic pneumonia, interstitial lung disease, Mendelson's syndrome, nasal congestion, pneumonitis, pulmonary embolism, pulmonary toxicity, respiratory disorder, respiratory distress, respiratory failure.

cerebral hematoma, depressed level of consciousness, disturbance in attention, dystonia, hypoaesthesia, intercostal neuralgia, intracranial pressure increased, lethargy, loss of consciousness, motor neurone disease, myasthenia gravis, neuropathy peripheral, poor quality sleep, radiculopathy, sedation, sensory disturbance, somnolence.

congenital central nervous system anomaly, congenital foot malformation, exomphalos, talipes.

alopecia, drug eruption, hyperhidrosis, pemphigoid, pruritus, rash, rash popular, skin discolouration, skin exfoliation, skin nodule.

amyotrophy, arthralgia, back pain, muscle rigidity, myalgia, pain in extremity, rhabdomyolysis, shoulder pain.

hepatitis B, herpes zoster infection neurological, lobar pneumonia, urinary tract infection.

Very common: abnormal liver function test. Uncommon: increased gamma glutamyl transferase, increased alkaline phosphatase, positive direct Coombs test, increased gamma globulins. Rare: increased lactic dehydrogenase.

Uncommon: bone neoplasm, lung carcinoma, neoplasm, prostate carcinoma, thyroid neoplasia. Rare: enlarged uterine fibroids.

gastric cancer, lung neoplasm malignant, non-Hodgkin's lymphoma.

blood pressure increased, flushing.

disseminated intravascular coagulation, granulocytopenia, lymphopenia, methaemoglobinaemia, normochromic normocytic anaemia, pancytopenia, platelet count decreased, prothrombin time shortened, red blood cell count decreased, thrombocytopenia, thrombocytopenic purpura, white blood cell count decreased, white blood cell count increased.

anxiety, completed suicide, depression, mental disorder, mental status change, psychiatric symptom, psychiatric disorder, restlessness.

abdominal pain lower, abdominal pain upper, dysphagia, gastrointestinal disorders, gastrointestinal dysplasia, illeus, illeus paralytic, intestinal functional disorder, intestinal obstruction, mouth ulceration, oesophagitis, pancreatitis acute.

postmenopausal haemorrhage.

blood methaemoglobin present, blood potassium decreased, decreased appetite, dehydration, diabetic ketoacidosis, hyperamylasaemia, hyperlipidaemia, lactic acidosis.

atrial fibrillation, cardiac failure, cardiac murmur, congestive cardiomyopathy, cor pulmonale, heart rate decreased, myocardial infarction, myocardial ischaemia.

chest pain, condition aggravated, death, disease progression, general physical health deterioration, inflammation, influenza like illness, malaise, pyrexia, sudden death.

Rare: deafness, ear pain, hyperacusis, vestibular disorder.

anuria, blood creatinine increased, dysuria, pancreatorenal syndrome, renal failure, renal failure acute, renal impairment.

This section provides the adverse drug reactions not listed above which have been reported through post-market surveillance. Although a causal relationship with RILUTEK may be suspected, other causes can not be excluded. The adverse drug reactions (ADRs) have been classified as per the MEDRA terminology. In some cases, the ADRs have been re-classified so that like-reactions are grouped together.

cholestasis, cytolytic hepatitis, hepatitis cholestatic, hepatitis fulminant, hepatocellular damage, hepatotoxicity.

intra-uterine death.

The most commonly observed adverse events associated with the use of RILUTEK, more frequently than with placebo treatment were: asthenia, nausea, elevations in liver function tests, dizziness, decreased lung function, diarrhea, abdominal pain, pneumonia, vomiting, vertigo, circumoral paresthesia, anorexia and somnolence.

Approximately 14% (n=199) of the 1396 individuals with ALS who received RILUTEK in clinical trials discontinued treatment because of an adverse event. Of those patients who discontinued due to adverse events, the most commonly reported associated adverse events were nausea, abdominal pain, constipation and ALT elevations.

Hepatitis, anaphylactoid reaction, angioedema and pancreatitis have been reported in isolated cases.

Uncommon: anaphylactoid reaction. Rare: angioedema.

Uncommon: diabetes mellitus, hypokalemia, hyponatremia, increased appetite. Rare: hypercalcemia, hypercholesteremia, tetany.

The safety and efficacy of RILUTEK in any neurodegenerative disease occurring in children or adolescents have not been established.

In controlled clinical trials, about 30% of patients were over 65. There were no differences in adverse effects between younger and older patients. A brief discussion can be found in the appropriate sections (see Warnings and Precautions, Special Populations, Geriatrics (>65 years) and Action and Clinical Pharmacology, Special Populations and Conditions, Geriatrics).

RILUTEK is contraindicated in patients who have hepatic disease or who have baseline transaminases greater than 3 times the ULN (upper limit of normal) (see Contraindications).

RILUTEK should be used with caution in patients with a history of abnormal liver function, with known concomitant liver insufficiency or in patients with elevations in any of serum transaminase (ALT; AST), bilirubin, or gamma-glutamyl transferase (GGT) levels. Baseline elevations of several liver function tests (especially including elevated bilirubin) should preclude the use of RILUTEK (see Contraindications; Dosage and Administration, Special Populations, Hepatic Insufficiency; Adverse Reactions, Abnormal Hematologic and Clinical Chemistry Findings).

Liver chemistries should be monitored in all patients on RILUTEK as the drug can increase serum aminotransferase, even in patients without a prior history of liver abnormality. Serum ALT levels should be measured every month during the first 3 months of treatment, every 3 months during the remainder of the first year, and periodically thereafter (see Warnings and Precautions, Monitoring and Laboratory Tests).

There were uncommon instances of jaundice and hepatitis.

RILUTEK should be discontinued if the ALT levels increase to 5× the ULN. There is no experience with dose reduction or rechallenge in patients who have developed an increase of ALT to 5 × ULN. Readministration of RILUTEK to patients in this situation cannot be recommended. In cases of RILUTEK-induced hepatic injury manifested by elevated liver enzymes, the effect of the hepatic injury on RILUTEK metabolism is unknown (see Action and Clinical Pharmacology, Special Populations and Conditions, Hepatic Insufficiency).

Experience in almost 800 ALS patients indicates that about 50% of RILUTEK-treated patients will experience at least one ALT level above the ULN, about 8% will have elevations >3×ULN, and about 2% of patients will have elevations >5×ULN. A single non-ALS patient with epilepsy treated with concomitant carbamazepine and phenobarbital experienced marked, rapid elevations of liver enzymes with jaundice (ALT 26×ULN, AST 17×ULN, and bilirubin 11×ULN) four months after starting RILUTEK; these returned to normal 7 weeks after treatment discontinuation.

Maximum increases in serum ALT usually occurred within 3 months after the start of RILUTEK therapy and were usually transient when <5×ULN. In trials, if ALT levels were <5×ULN, treatment continued and ALT levels usually returned to below 2×ULN within 2 to 6 months. However, treatment in studies was discontinued if ALT levels exceeded 5×ULN; in these cases, the levels generally returned to less than 2×ULN within 2 to 6 months.

See Action and Clinical Pharmacology, Special Populations and Conditions, Gender.

There are no adequate and well-controlled studies in pregnant women and RILUTEK is known to cross the placental barrier in rats. RILUTEK must not be used in pregnant women (see Contraindications).

In the pregnant rat, the transfer of ¹⁴C-riluzole across the placenta to the foetus has been detected. Oral administration of riluzole to pregnant animals during the period of organogenesis caused embryotoxicity in rats and rabbits at doses of 27 mg/kg and 60 mg/kg, respectively, or 2.6 and 11.5 times, respectively, the recommended maximum human daily dose on a mg/m² basis. Evidence of maternal toxicity was also observed at these doses.

When administered to rats prior to and during mating (males and females) and throughout gestation and lactation (females), RILUTEK produced adverse effects on pregnancy (decreased implantations, increased intrauterine death) and offspring viability and growth at an oral dose of 15 mg/kg or 1.5 times the maximum daily dose on a mg/m² basis.

See Contraindications, Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries and Special Populations, Hepatic Insufficiency, Action and Clinical Pharmacology, Special Populations and Conditions, Hepatic Insufficiency; Dosage and Administration, Special Populations, Hepatic Insufficiency.

See Contraindications; Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries; Action and Clinical Pharmacology, Special Populations and Conditions, Hepatic Insufficiency; Dosage and Administration, Special Populations, Hepatic Insufficiency.

Patients should be warned to report any febrile illness to their physicians. The report of a febrile illness should prompt treating physicians to check white blood cell counts and to discontinue RILUTEK in case of neutropenia (see Adverse Reactions, Abnormal Hematologic and Clinical Chemistry Findings).

Among approximately 5000 patients given RILUTEK for ALS, there were three cases of marked neutropenia (absolute neutrophil count less than 500/mm³), all seen within the first 2 months of RILUTEK treatment. In one case, neutrophil counts rose on continued treatment. In a second case, counts rose after therapy was stopped. A third case was more complex, with marked anemia as well as neutropenia and the etiology of both is uncertain.

In the two controlled trials in patients with ALS, the frequency with which values for hemoglobin, hematocrit, and erythrocyte counts fell below the lower limit of normal was greater in RILUTEK-treated patients than in placebo-treated patients; however, these changes were mild and transient. The proportions of patients observed with abnormally low values for these parameters showed a dose-response relationship. Only one patient was discontinued from treatment because of severe anemia. The significance of this finding is unknown.

See Action and Clinical Pharmacology, Special Populations and Conditions, Race.

RILUTEK is not recommended for use in patients with impaired renal function, as studies at repeated doses have not been conducted in this population (see Dosage and Administration, Special Populations, Renal Insufficiency; Action and Clinical Pharmacology, Special Populations and Conditions, Renal Insufficiency).

The safety and efficacy of RILUTEK in any neurodegenerative disease occurring in children or adolescents have not been established.

In controlled clinical trials, about 30% of patients were over 65. There were no differences in adverse effects between younger and older patients. Based on pharmacokinetic data, there are no special instructions for the use of RILUTEK in this population (see Action and Clinical Pharmacology, Special Populations and Conditions, Geriatrics).

In rat studies, ¹⁴C-riluzole was detected in maternal milk. It is not known whether riluzole is excreted in human breast milk. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from RILUTEK, RILUTEK must not be used in nursing women (see Contraindications).

Because of risks of hepatitis and jaundice, serum transaminases, including ALT levels, should be measured before and during therapy with RILUTEK. Serum ALT levels should be measured every month during the first 3 months of treatment, every 3 months during the remainder of the first year, and periodically thereafter. Serum ALT levels should be measured more frequently in patients who develop elevated ALT levels (see Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries).

As noted in the Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries, there is no experience with continued treatment of patients once ALT exceeds 5×ULN. If a decision is made to continue to treat these patients, frequent monitoring (at least weekly) of complete liver function is recommended. Treatment should be discontinued if ALT exceeds 10×ULN or if clinical jaundice develops. Because there is no experience with rechallenge of patients who have had RILUTEK discontinued for ALT >5×ULN, no recommendations about restarting RILUTEK can be made.

The AUC of riluzole after single oral dose of 50 mg increases by about 1.7 fold in n=6 subjects with mild chronic liver insufficiency and by about 3 fold in n=6 subjects with moderate chronic liver insufficiency, compared to n=12 healthy subjects. The pharmacokinetics of RILUTEK have not been studied in patient with severe hepatic impairment (see Contraindications; Warnings and Precautions, General, Liver Injury/Monitoring Liver Chemistries; Dosage and Administration, Recommended Dose and Dosage Adjustment, Special Populations, Hepatic Insufficiency).

The pharmacokinetic parameters of riluzole after multiple dose administration (4.5 days of treatment at 50 mg riluzole BID) in n=18 elderly and n=18 young subjects are not affected in the elderly (>70 years). (See Warnings and Precautions, Special Populations, Geriatrics (>65 years).)

Riluzole is extensively distributed throughout the body and has been shown to cross the blood brain barrier. The volume of distribution of riluzole is about 3.4 L/kg.

Riluzole is 96% bound to plasma proteins, mainly to albumin and lipoproteins over the clinical concentration range.

Pharmacokinetics are linear over a dose range of 25-100 mg given every 12 hours.

Riluzole is rapidly absorbed after oral administration with maximal plasma concentrations occurring within 60 to 90 minutes. Riluzole is well absorbed (approximately 90%), with average absolute oral bioavailability of about 60% (CV=30%). A high fat meal decreases absorption, reducing AUC by about 20% and peak blood levels by about 45%.

With multiple-dose administration, riluzole accumulates in plasma by about 2 fold and steady-state is reached in less than 5 days.

The 50 mg market tablet was equivalent, with respect to AUC, to the tablet used in the dose ranging clinical trials, while the C_max was approximately 30% higher. Both tablets have been used in clinical trials. However, if doses greater than those recommended are given, it is likely that higher plasma levels will be achieved, the safety of which has not been established (see Dosage and Administration).

The etiology and pathogenesis of ALS are not known, although a number of hypotheses have been advanced. One hypothesis is that motor neurons, made vulnerable through either genetic predisposition or environmental factors, are injured by glutamate. In some cases of familial ALS the enzyme superoxide dismutase has been found to be defective.

The mode of action of RILUTEK is unknown. Its pharmacological properties include the following, some of which may be related to its effect: 1) an inhibitory effect on glutamate release, 2) inactivation of voltage-dependent sodium channels, and 3) ability to interfere with intracellular events that follow transmitter binding at excitatory amino acid receptor.

A clinical study was conducted in Germany to evaluate the pharmacokinetics of riluzole and its metabolite N-hydroxyriluzole following repeated oral administration twice daily for 8 days in n=16 healthy Japanese and n=16 Caucasian adult males, with the former having Japanese citizenship, and resident in North America or Europe for <10 years. Results showed no difference in mean pharmacokinetic parameters between the two groups, either for RILUTEK or the major metabolite.

Cigarette smoking is known to induce CYP 1A2. Patients who smoke cigarettes would be expected to eliminate riluzole faster. There is no information, however on the effect of, or need for, dosage adjustment in these patients.

Following a single 150 mg dose of ¹⁴C-riluzole to 6 healthy males, 90% and 5% of the radioactivity was recovered in the urine and feces respectively over a period of 7 days. Glucuronides accounted for more than 85% of the metabolites in urine. Only 2% of a riluzole dose was recovered in the urine as unchanged drug.

The mean elimination half-life of riluzole is 12 hours (CV=35%) after repeated doses.

After a single oral dose of riluzole 50 mg, no significant difference in mean pharmacokinetic parameters between n=12 subjects with moderate or severe chronic renal insufficiency (10 to 50 mL/min) and n=12 healthy volunteers were observed. (See Warnings and Precautions, Special Populations, Renal Insufficiency, Dosage and Administration, Recommended Dose and Dosage Adjustment, Special Populations, Renal Insufficiency.)

In one placebo-controlled clinical trial with population pharmacokinetics, RILUTEK mean clearance was found to be 30% lower in female patients (corresponding to an approximate increase in AUC of 45%). CYP 1A2 activity has been reported to be lower in women than in men. Therefore, a gender effect on riluzole kinetics may be expected in women, resulting in higher blood concentrations of riluzole and its metabolites. However, regarding benefits or adverse events of riluzole, no gender effect was seen in controlled trials.

Riluzole is extensively metabolized to six major and a number of minor metabolites, not all of which have been identified. Some metabolites appear pharmacologically active in in vitro assays. The metabolism of riluzole is mostly hepatic and consists of cytochrome P450-dependent hydroxylation and glucuronidation.

There is marked inter-individual variability in the clearance of riluzole, probably attributable to variability of CYP 1A2 activity, the principal isozyme involved in N-hydroxylation.

In vitro studies using liver microsomes show that hydroxylation of the primary amine group producing N-hydroxyriluzole (RPR 112512), is the main metabolic pathway in human, monkey, dog and rabbit. In humans, cytochrome P450 1A2 is the principal isozyme involved in N-hydroxylation. In vitro studies predict that CYP 2D6, CYP 2C19, CYP 3A4 and CYP 2E1 are unlikely to contribute significantly to riluzole metabolism in humans. Whereas direct glucuroconjugation of riluzole (involving the glucurotransferase isoform UGT-HP4) is very slow in human liver microsomes, N-hydroxyriluzole is readily conjugated at the hydroxylamine group resulting in the formation of O-(>90%) and N-glucuronides.

RILUTEK has also been shown, in a single study, to delay median time to death in a transgenic mouse model of ALS. These mice express human superoxide dismutase bearing one of the mutations found in one of the familial forms of human ALS.

It is also neuroprotective in various in vivo experimental models of neural injury involving excitotoxic mechanisms. In vitro, riluzole protected cultured rat motor neurons from the excitotoxic effects of glutamic acid and prevented the death of cortical neurons induced by anoxia.

Due to its blockade of glutamatergic neuro-transmission, riluzole also exhibits myorelaxant and sedative properties in animal models at doses of 30 mg/kg (about 20 times the recommended human daily dose) and anticonvulsant properties at a dose of 2.5 mg/kg (about 2 times the recommended human daily dose).