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Stiripentol Capsules and Powder for Oral Suspension

TABLE OF CONTENTS

1. DESCRIPTION 8. USE IN SPECIFIC POPULATIONS
2. INDICATIONS AND USAGE 9. OVERDOSAGE
3. DOSAGE AND ADMINISTRATION 10. MECHANISM OF ACTION
4. CONTRAINDICATIONS 11. PHARMACODYNAMICS
5. WARNINGS AND PRECAUTIONS 12. PHARMACOKINETICS
6. ADVERSE REACTIONS 13. HOW SUPPLIED/STORAGE AND HANDLING
7. DRUG INTERACTIONS

 

1. DESCRIPTION

Stiripentol is a white to pale yellow crystalline powder with a bitter taste; it is practically insoluble in water (at 25°C), sparingly soluble in chloroform, and soluble in acetone, ethanol, ether, acetonitrile, and dichloromethane. The melting point is approximately 75°C. The pKa is 14.2, and measurement of the partition coefficient (water-octanol) provides a Log P value of 2.94. Chemical name: 4,4-dimethyl-1-[3,4-(methylendioxyphenyl)-1-pentene-3-ol

Empirical formula: C14H18O3 - Molecular weight: 234.3 g/mol

Capsules

Stiripentol capsules contain 250 mg (size 2: pink) or 500 mg (size 0: white) of stiripentol. Capsules also contain the following inactive ingredients: erythrosine (250 mg capsule only), gelatin, indigotine (250 mg capsule only), magnesium stearate, povidone, sodium starch glycolate, titanium dioxide.

Powder for Suspension

Stiripentol powder for oral suspension packets contain 250 mg or 500 mg of stiripentol. Stiripentol packets also contain the following inactive ingredients: aspartame, carmellose sodium, erythrosine, glucose, hydroxyethylcellulose, povidone, sodium starch glycolate, sorbitol, titanium dioxide, fruit flavor (acacia, Bergamot oil, hypromellose, maltodextrin, sorbitol, and vanillin).

2. INDICATIONS AND USAGE

Stiripentol is indicated for the treatment of seizures associated with Dravet syndrome (DS) in patients 2 years of age and older taking clobazam. There are no clinical data to support the use of stiripentol as monotherapy in Dravet syndrome.

3. DOSAGE AND ADMINISTRATION

3.1 Laboratory Tests Prior to First Dose of Stiripentol

Hematologic testing should be obtained prior to starting treatment with stiripentol [see Warnings and Precautions (5.3)].

3.2 Dosing Information

The recommended oral dosage of stiripentol is 50 mg/kg/day, administered in 2 or 3 divided doses (i.e., 16.67 mg/kg three times daily or 25 mg/kg twice daily). If the exact dosage is not achievable given the available strengths, round to the nearest possible dosage, which is usually within 50 mg to 150 mg of the recommended 50 mg/kg/day. A combination of the two stiripentol strengths can be used to achieve this dosage. The maximum recommended total dosage is 3,000 mg/day.

3.3 Gradual Withdrawal

As is advisable for most antiepileptic drugs, if stiripentol treatment is discontinued, the drug should be withdrawn gradually to minimize the risk of increased seizure frequency and status epilepticus [see Warnings and Precautions (5.4)].

In situations where rapid withdrawal of stiripentol is medically required, appropriate monitoring is recommended.

3.4 Important Administration Instructions

Stiripentol Capsules

Stiripentol capsules must be swallowed whole with a glass of water during a meal. Capsules should not be broken or opened.

Stiripentol Powder for Oral Suspension

Stiripentol should be mixed in a glass of water (100 mL) and should be taken immediately after mixing during a meal. To be sure there is no medicine left in the glass, add a small amount of water (25 mL) to the drinking cup and drink all of the mixture [see Instructions for Use].

3.5 Missed Dose

A missed dose should be taken as soon as possible. If it is almost time for the next dose, the missed dose should not be taken. Instead, the next scheduled dose should be taken. Doses should not be doubled.

4. CONTRAINDICATIONS

None.

5. WARNINGS AND PRECAUTIONS

5.1 Somnolence

Stiripentol can cause somnolence. In controlled studies in patients with Dravet syndrome, the incidence of somnolence was 67% in stiripentol-treated patients, compared to 23% in patients on placebo. All patients in both groups were on concomitant clobazam, which is also known to cause somnolence. Co-administration of stiripentol with clobazam results in increased levels of clobazam and its active metabolite [see Drug Interactions (7.1)]. Other central nervous system CNS depressants, including alcohol, could potentiate the somnolence effect of stiripentol.

Prescribers should monitor patients for somnolence. If somnolence occurs during co-administration with clobazam, consider an initial reduction of clobazam by 25%. If somnolence persists, further clobazam reduction by an additional 25% should be considered, as should adjustment of the dosage of other concomitant anticonvulsant drugs with sedating properties. Prescribers should caution patients against engaging in hazardous activities requiring mental alertness, such as operating dangerous machinery or motor vehicles, until the effect of stiripentol on mental alertness is known.

5.2 Decreased Appetite and Decreased Weight

Stiripentol can cause decreases in appetite and weight. In controlled studies in patients with Dravet syndrome, the incidence of decreased appetite was 46% in stiripentol-treated patients, compared to 10% in patients on placebo. The incidence of decreased weight was 27% in stiripentol-treated patients, compared to 6% in patients on placebo. Nausea and vomiting also occurred more frequently in stiripentol-treated patients [see Adverse Reactions (6.1)]. Given the frequency of these adverse reactions, the growth of pediatric patients treated with stiripentol should be carefully monitored. In some cases, decreasing the dose of concomitant valproate by 30% per week can reduce the decrease in appetite and weight.

5.3 Neutropenia and Thrombocytopenia

Stiripentol can cause a significant decline in neutrophil count. In controlled studies in patients with Dravet syndrome, there were 31 patients treated with stiripentol who had both a baseline and end-of-study neutrophil count obtained. A decrease in neutrophil count from normal at baseline to less than 1500 cells/mm3 during the trial was observed in 13% of these stiripentol-treated patients, but not in any placebo-treated patients.

Stiripentol can cause a significant decline in platelet count. In controlled studies in patients with Dravet syndrome, there were 31 patients treated with stiripentol who had both a baseline and end-of-study platelet count. A decrease in platelet count from normal at baseline to less than 150,000/μL during the trial was observed in 13% of these stiripentol-treated patients, but not in any placebo-treated patients.

Hematologic testing should be obtained prior to starting treatment with stiripentol, and then every 6 months.

5.4 Withdrawal Symptoms

As with most antiepileptic drugs, stiripentol should generally be withdrawn gradually to minimize the risk of increased seizure frequency and status epilepticus.

In situations where rapid withdrawal of stiripentol is required (e.g., in the setting of a serious adverse reaction), appropriate monitoring is recommended.

5.5 Risks in Patients with Phenylketonuria

Phenylalanine can be harmful to patients with phenylketonuria (PKU). Stiripentol Powder for Suspension contains phenylalanine, a component of aspartame. Each 250 mg packet contains 1.40 mg phenylalanine; each 500 mg packet contains 2.80 mg phenylalanine. Before prescribing stiripentol powder for suspension to a patient with PKU, consider the combined daily amount of phenylalanine from all sources, including stiripentol powder for suspension.

Stiripentol capsules do not contain phenylalanine.

5.6 Suicidal Behavior and Ideation

AEDs, including stiripentol, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.

Pooled analyses of 199 placebo-controlled clinical trials (mono-and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted relative risk 1.8, 95% confidence interval [CI]:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED treated patients was 0.43%, compared to 0.24% among 16,029 placebo treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug treated patients in the trials and none in placebo treated patients, but the number is too small to allow any conclusion about drug effect on suicide.

The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.

The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5-100 years) in the clinical trials analyzed. Table 1 shows absolute and relative risk by indication for all evaluated AEDs.

Table 1. Risk by Indication for Antiepileptic Drugs in the Pooled Analysis

The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications.

Anyone considering prescribing stiripentol or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated.

Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers.

6. ADVERSE REACTIONS

The following serious or otherwise clinically significant adverse reactions are described elsewhere in the labeling:

• Somnolence [see Warnings and Precautions (5.1)]

• Decreased Appetite and Decreased Weight [see Warnings and Precautions (5.2)]

• Neutropenia and Thrombocytopenia [see Warnings and Precautions (5.3)]

• Withdrawal Symptoms [see Warnings and Precautions (5.4)]

• Risks in Patients with Phenylketonuria [see Warnings and Precautions (5.5)]

• Suicidal Behavior and Ideation [see Warnings and Precautions (5.6)]

6.1 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 clinical trials of another drug, and may not reflect the rates observed in practice.

During its development for the treatment of seizures associated with Dravet syndrome, stiripentol was administered to 55 healthy male volunteers and 438 patients with Dravet syndrome, including 310 patients treated for 12 months or more. The conditions and duration of exposure varied greatly, and included single-and multiple-dose clinical pharmacology studies in healthy male volunteers, 2 randomized, double-blind, placebo-controlled, 12-week studies in patients with Dravet syndrome (Study 1 and Study 2), and open-label long-term studies.

In Study 1 and Study 2, 33 patients received stiripentol and 31 patients received placebo for a treatment duration of 8 weeks. Adverse reactions from these trials are presented below. Approximately 53% of patients were female and the mean age was 9.2 years. All patients were taking clobazam and valproate.

There were 2 patients in whom adverse reactions led to discontinuation of stiripentol treatment: one patient had an adverse reaction of status epilepticus; the second patient had drowsiness, balance impaired and sialorrhea.

The most common adverse reactions, occurring in at least 10% of stiripentol-treated patients and more frequently than on placebo, included somnolence (67%), decreased appetite (45%), agitation (27%), ataxia (27%), weight decreased (27%), hypotonia (24%), nausea (15%), tremor (15%), dysarthria (12%), and insomnia (12%).

Table 2 lists the adverse reactions that occurred in 5% or more of stiripentol-treated patients and at a rate greater than in patients on placebo in the 2 randomized, double-blind, placebo-controlled, clinical trials in patients with Dravet syndrome (Study 1 and Study 2).

Table 2. Adverse Reactions in 5% or More of Stiripentol-Treated Patients and More Frequently than on Placebo in Patients with Dravet Syndrome (Study 1 and Study 2)

7. DRUG INTERACTIONS

7.1 Effect of Stiripentol on Other Drugs

CYP1A2, CYP2B6, CYP3A4, CYP2C8, CYP2C19, P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP) Substrates

In vitro data show that stiripentol is both an inhibitor and inducer of CYP1A2, CYP2B6, and CYP3A4. Because of potential drug-drug interactions, consider dose adjustment of CYP1A2 substrates (e.g., theophylline, caffeine), CYP2B6 substrates (e.g., sertraline, thiotepa), and CYP3A4 substrates (e.g., midazolam, triazolam, quinidine), as clinically appropriate, when administered concomitantly with stiripentol.

Because of potential inhibition of enzyme/transporter activity, consider a reduction in dosage of substrates of CYP2C8, CYP2C19 (e.g., diazepam, clopidogrel), P-gp (e.g., carbamazepine), and BCRP (e.g., methotrexate, prazosin, glyburide), if adverse reactions are experienced when administered concomitantly with stiripentol.

Clobazam

Co-administration of stiripentol (which inhibits CYP 3A4 and 2C19) with clobazam results in increased plasma concentrations of clobazam (a substrate of CYP3A4) and norclobazam, the active metabolite of clobazam (a substrate of CYP2C19) [see Clinical Pharmacology]. This may increase the risk of clobazam-related adverse reactions. Consider a reduction in dosage of clobazam if adverse reactions are experienced when co-administered with stiripentol [see Warnings and Precautions (5.1)].

7.2 Effect of Other Drugs on Stiripentol

Induction-based interactions leading to decreases in stiripentol concentrations are possible when co-administered with a potent CYP1A2, CYP3A4, or CYP2C19 inducer, such as rifampin, phenytoin, phenobarbital and carbamazepine, as these enzymes all metabolize stiripentol. Concomitant use of strong inducers with stiripentol should be avoided, or dosage adjustments should be made.

7.3 CNS Depressants and Alcohol

Concomitant use of stiripentol with other CNS depressants, including alcohol, may increase the risk of sedation and somnolence [see Warnings and Precautions (5.1)].

8. USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, such as stiripentol, during pregnancy. Physicians are advised to recommend that pregnant patients taking stiripentol enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll free number 1-888-233-2334, and must be done by patients themselves or their caregiver. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.

Risk Summary

There are no adequate data on the developmental risks associated with the use of stiripentol in pregnant women. Administration of stiripentol to pregnant animals produced evidence of developmental toxicity, including increased incidences of fetal malformations, increased embryofetal and pup mortality, and decreased embryofetal and pup growth, at maternal doses lower than the recommended clinical dose [see Animal Data].

The background risk of major birth defects and miscarriage in Dravet syndrome is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Data

Animal Data

Oral administration of stiripentol (0, 50, 200, or 800 mg/kg/day) to pregnant mice throughout the period of organogenesis resulted in increased embryofetal mortality and decreased fetal body weights at all doses and an increased incidence of malformations at the high dose, with no evidence of maternal toxicity. The lowest effect dose for developmental toxicity in mice (50 mg/kg/day) was less than the recommended human dose (RHD) of 50 mg/kg/day on a body surface area (mg/m2) basis.

Oral administration of stiripentol (0, 50, 200, or 800 mg/kg/day) to pregnant rabbits throughout organogenesis resulted in increased embryofetal mortality at the mid and high dose and decreased fetal body weights at all doses. The mid and high doses were associated with maternal toxicity. The lowest effect dose for developmental toxicity in rabbits (50 mg/kg/day) was less than the RHD on a mg/m2 basis.

Oral administration of stiripentol (0, 50, 200, or 800 mg/kg/day) to rats throughout pregnancy and lactation resulted in decreased pup survival, decreased pup body weights at birth and throughout lactation, and deficits in pup reflex development at the high dose, which was also associated with maternal toxicity. The no-effect dose for pre-and postnatal developmental toxicity in rats (200 mg/kg) was less than the RHD on a mg/m2 basis.

8.2 Lactation

Risk Summary

There are no data on the presence of stiripentol in human milk, the effects on the breastfed infant, or the effects on milk production.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for stiripentol and any potential adverse effects on the breastfed infant from stiripentol or from the underlying maternal condition.

8.4 Pediatric Use

The safety and effectiveness of stiripentol for the treatment of seizures associated with Dravet syndrome in patients taking clobazam have been established in patients 2 to 18 years of age. Use of stiripentol in this pediatric population is supported by 2 multicenter placebo-controlled double-blind randomized studies [see Clinical Studies].

Safety and effectiveness in pediatric patients below the age of 2 years have not been established.

8.5 Geriatric Use

Clinical studies of stiripentol in Dravet syndrome did not include patients ≥65 years of age to determine whether they respond differently from younger patients. The possibility of age-associated hepatic and renal function abnormalities should be considered when using stiripentol in patients ≥65 years of age [see Clinical Pharmacology].

8.6 Renal Impairment

There is no formal study of the pharmacokinetics and metabolism of stiripentol in patients with renal impairment. However, since stiripentol metabolites are eliminated mainly through the kidney, administration to patients with moderate or severe renal impairment is not recommended.

8.7 Hepatic Impairment

There has been no formal study of the pharmacokinetics of stiripentol in patients with liver impairment. However, since the drug is mainly metabolized by the liver, administration to patients with moderate or severe liver impairment is not recommended.

9. OVERDOSAGE

There are no data concerning overdose in humans. In mice treated with high doses of stiripentol (600 to 1800 mg/kg i.p.), decreased motor activity and decreased respiration were observed. Treatment of an overdose should be supportive (symptomatic measures in intensive care units).

For management of a suspected drug overdose, contact your regional Poison Control Center.

10. MECHANISM OF ACTION

The mechanism by which stiripentol exerts its anticonvulsant effect in humans is unknown. Possible mechanisms of action include direct effects mediated through the gamma-aminobutyric acid (GABA)A receptor and indirect effects involving inhibition of cytochrome P450 activity with resulting increase in blood levels of clobazam and its active metabolite.

11. PHARMACODYNAMICS

There are no relevant data on the pharmacodynamic effects of stiripentol.

12. PHARMACOKINETICS

The following pharmacokinetic properties of stiripentol have been found in studies in adult healthy volunteers and adult patients. Systemic exposure of stiripentol increases in a greater than dose proportional manner from 500 mg to 2000 mg.

Absorption: The median time to stiripentol peak plasma concentration is 2 to 3 hours.

Distribution: Protein binding of stiripentol is 99%.

Elimination: The elimination half-life of stiripentol ranges from 4.5 to 13 hours, increasing with doses of 500 mg, 1000 mg and 2000 mg.

Metabolism: On the basis of in vitro studies, the main liver cytochrome P450 (CYP) isoenzymes involved in metabolism are considered to be CYP1A2, CYP2C19, and CYP3A4.

Specific Populations

The effect of age (≥ 65 years), race, renal and hepatic impairment on stiripentol pharmacokinetics is unknown [see Use in Specific Populations (85, 8.6, 8.7)]. Sex does not have a clinically significant effect on the pharmacokinetics of stiripentol.

Pediatric Patients: In a study of children (median age 7.3 years) with Dravet syndrome treated with stiripentol, valproate, and clobazam, the apparent clearance and volume of distribution of stiripentol were related to body weight. Elimination half-life increased from 8.5 hr (for 10 kg) to 23.5 hr (for 60 kg).

Drug Interaction Studies

In Vitro Studies

The metabolic pathway for stiripentol has not been clearly elucidated. Stiripentol is a substrate of several CYP enzymes, including CYP1A2, CYP2C19, and CYP3A4. Stiripentol inhibits and induces CYP1A2, CYP2B6, and CYP3A4. Stiripentol also inhibits CYP2C8, CYP2C19, and drug transporters, including P-gp and BCRP, at clinically relevant concentrations [see Drug Interactions (7.1)].

Clinical Studies

Antiepileptic drugs: Co-administration of clobazam with stiripentol increased concentrations of clobazam by approximately 2-fold and norclobazam (clobazam active metabolite) by 5-fold [see Drug Interactions (7.1)].

13. HOW SUPPLIED/STORAGE AND HANDLING

How Supplied:

DIACOMIT Capsules

• 250 mg: size 2, pink, and imprinted with “Diacomit” and “250mg” are supplied as follows:

Bottles of 60 NDC 68418-7939-6

• 500 mg: size 0, white, and imprinted with “Diacomit” and “500mg” are supplied as follows:

Bottles of 60 NDC 68418-7940-6

Powder for Oral Suspension

• 250 mg: pale pink fruit flavored powder packaged in packets are supplied as follows:

Cartons of 60 NDC 68418-7941-6

• 500 mg: pale pink fruit flavored powder packaged in packets are supplied as follows:

Cartons of 60 NDC 68418-7942-6

Storage and Handling:

Store in a dry place at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature]. Store in original package to protect from light.

Rx only

Rev 08/18