Topiramate

Topiramate
Adult Indications & Dosage
Pediatric Indications & Dosage
Contraindications
Warnings & Precautions
Adverse Reactions
Drug Interactions
Use in Specific Populations
Administration & Monitoring
Overdosage
Pharmacology
Clinical Studies
How Supplied
Images
Patient Counseling Information
Precautions with Alcohol
Brand Names
Look-Alike Names

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]

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Overview

Topiramate is a Mood Stabilizer that is FDA approved for the {{{indicationType}}} of Lennox-Gastaut syndrome (adjunct), migraine (prophylaxis), partial seizure (initial monotherapy), partial seizure(adjunct), tonic-clonic seizure, primary generalized (adjunct), tonic-clonic seizure, primary generalized (initial monotherapy). Common adverse reactions include flushing, serum bicarbonate level abnormal, loss of appetite, weight decreased, infectious disease, confusion, dizziness, impaired cognition, impaired, psychomotor performance, memory impairment, paresthesia, reduced concentration span, somnolence, feeling nervous, mood disorder, fatigue, fever.

Adult Indications and Dosage

FDA-Labeled Indications and Dosage (Adult)

• Lennox-Gastaut syndrome

• Start 25 to 50 mg/day PO, increase dosage by 25 to 50 mg/day at 1-week intervals to maintenance dose of 200 to 400 mg/day in 2 divided doses.

• Migraine prophylaxis

• 100 mg/day PO administered in 2 divided doses; 25 mg in the evening for 1 week, 25 mg twice daily for 1 week, 25 mg in the morning and 50 mg in the evening for 1 week, and then 50 mg twice daily.

• Partial seizure, initial monotherapy

• 25 mg PO twice daily; second week 50 mg PO twice daily, third week 75 mg PO twice daily, fourth week 100 mg PO twice daily, fifth week 150 mg PO twice daily, sixth week (MAX dose) 200 mg PO

• Partial seizure; adjunct

• 25 to 50 mg/day PO; may increase dosage by 25 to 50 mg/day at 1-week intervals to the usual maintenance dose of 200 to 400 mg/day in 2 divided doses.

• Tonic-clonic seizure, primary generalized (adjunct)

• 25 to 50 mg/day ORALLY; may increase dosage by 25 to 50 mg/day at 1-week intervals to the usual maintenance dose of 400 mg/day in 2 divided doses.

• Tonic-clonic seizure, primary generalized (initial monotherapy).

• 25 mg PO twice daily (morning and evening); second week, 50 mg PO twice daily; third week, 75 mg PO twice daily; fourth week, 100 mg PO twice daily; fifth week, 150 mg PO twice daily; sixth week (MAX dose), 200 mg PO twice daily

Off-Label Use and Dosage (Adult)

Guideline-Supported Use

There is limited information about Off-Label Guideline-Supported Use of Topiramate in adult patients.

Non–Guideline-Supported Use

• Alcoholism
• Diabetes mellitus type 2 in obese (adjunct)
• Eating disorder.
• Essential tremor
• Obesity

There is limited information about Off-Label Non–Guideline-Supported Use of Topiramate in adult patients.

Pediatric Indications and Dosage

FDA-Labeled Indications and Dosage (Pediatric)

• Lennox-Gastaut syndrome

• 2 years or older for opamax(R) and Qudexy(TM) XR,
• 6 years or older for Trokendi XR(TM)

• Migraine prophylaxis

• 12 years or older for Topamax(R) only

• Partial seizure, initial monotherapy

• 2 years or older for Qudexy XR (TM)
• 10 years or older for Trokendi XR(TM),

• Partial seizure; adjunct

• 2 years or older for Topamax(R) and Qudexy(TM) XR,
• 6 years or older Trokendi XR(TM)

• Tonic-clonic seizure, primary generalized (adjunct)

• 2 years or older for Topamax(R) and Qudexy(TM) XR
• 6 years or older for Trokendi XR(TM)

• Tonic-clonic seizure, primary generalized (initial monotherapy)

• 2 years or older for Topamax(R)
• 10 years or older for Trokendi XR(TM) and Qudexy(TM) XR

Off-Label Use and Dosage (Pediatric)

Guideline-Supported Use

There is limited information about Off-Label Guideline-Supported Use of Topiramate in pediatric patients.

Non–Guideline-Supported Use

There is limited information about Off-Label Non–Guideline-Supported Use of Topiramate in pediatric patients.

Contraindications

There is limited information regarding Topiramate Contraindications in the drug label.

Warnings

• Acute myopia and secondary angle closure glaucoma: Untreated elevated intraocular pressure can lead to permanent visual loss. Discontinue Topiramate if it occurs
• Visual field defects: These have been reported independent of elevated intraocular pressure. Consider discontinuation of Topiramate
• Oligohydrosis and hyperthermia: Monitor decreased sweating and increased body temperature, especially in pediatric patients
• Metabolic acidosis: Measure baseline and periodic measurement of serum bicarbonate. Consider dose reduction or discontinuation of Topiramate if clinically appropriate
• Suicidal behavior and ideation: Antiepileptic drugs increase the risk of suicidal behavior or ideation
• Cognitive/neuropsychiatric: Topiramate may cause cognitive dysfunction. Use caution when operating machinery including automobiles. Depression and mood problems may occur
• Fetal toxicity: Topiramate use during pregnancy can cause cleft lip and/or palate
• Withdrawal of AEDs: Withdrawal of Topiramate should be done gradually
• Hyperammonemia and encephalopathy: Patients with inborn errors of metabolism or reduced mitochondrial activity may have an increased risk of hyperammonemia. Measure ammonia if encephalopathic symptoms occur
• Kidney stones: Avoid use with other carbonic anhydrase inhibitors, other drugs causing metabolic acidosis, or in patients on a ketogenic diet
• Hypothermia: Reported with concomitant valproic acid use

Adverse Reactions

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 clinical practice. In the topiramate study, a dose of 200 mg/day was administered to a limited number of patients; therefore, these results cannot be directly compared to immediate-release topiramate experience.
• The safety data presented below are from 249 patients with partial epilepsy on concomitant AEDs who participated in the topiramate study.
• Table 8 displays the incidence of treatment-emergent adverse reactions that occurred in ≥2% of patients and numerically greater than placebo.

This image is provided by the National Library of Medicine.

• In the controlled clinical study using topiramate, 8.9% of patients who received topiramate and 4.0% who received placebo discontinued as a result of treatment-emergent adverse reactions.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of topiramate. 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. The listing is alphabetized:

1. Bullous skin reactions, including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis,
2. Hepatic failure (including fatalities),
3. Hepatitis
4. Maculopathy
5. Pancreatitis
6. Pemphigus

Drug Interactions

• Oral Contraceptives

• The possibility of decreased contraceptive efficacy and increased breakthrough bleeding should be considered in patients taking combination oral contraceptive products with topiramate. Patients taking estrogen-containing contraceptives should be asked to report any change in their bleeding patterns. Contraceptive efficacy can be decreased even in the absence of breakthrough bleeding.

• Antiepileptic Drugs

• Concomitant administration of phenytoin or carbamazepine with topiramate decreased plasma concentrations of topiramate
• Concomitant administration of valproic acid and topiramate has been associated with hyperammonemia with and without encephalopathy. Concomitant administration of topiramate with valproic acid has also been associated with hypothermia (with and without hyperammonemia) in patients who have tolerated either drug alone. It may be prudent to examine blood ammonia levels in patients in whom the onset of hypothermia has been reported.
• Numerous AEDs are substrates of the CYP enzyme system. In vitro studies indicate that topiramate does not inhibit enzyme activity for CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4/5 isozymes. In vitro studies indicate that immediate-release topiramate is a mild inhibitor of CYP2C19 and a mild inducer of CYP3A4. The same drug interactions can be expected with the use of topiramate.

• CNS Depressants and Alcohol

• Topiramate is a CNS depressant. Concomitant administration of topiramate with other CNS depressant drugs or alcohol can result in significant CNS depression. Concomitant use of alcohol should be avoided

• Other Carbonic Anhydrase Inhibitors

• Concomitant use of topiramate, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g., zonisamide, acetazolamide or dichlorphenamide), may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation. Patients should be monitored for the appearance or worsening of metabolic acidosis when topiramate is given concomitantly with another carbonic anhydrase inhibitor

• Metformin

• Topiramate treatment can frequently cause metabolic acidosis, a condition for which the use of metformin is contraindicated. The concomitant use of topiramate and metformin is contraindicated in patients with metabolic acidosis

• Lithium

• In patients, there was an observed increase in systemic exposure of lithium following topiramate doses of up to 600 mg per day. Lithium levels should be monitored when co-administered with high-dose topiramate

Use in Specific Populations

Pregnancy

Pregnancy Category (FDA): D

• Topiramate can cause fetal harm when administered to a pregnant woman. Data from pregnancy registries indicate that infants exposed to topiramate in utero have increased risk for cleft lip and/or cleft palate (oral clefts). When multiple species of pregnant animals received topiramate at clinically relevant doses, structural malformations, including craniofacial defects, and reduced fetal weights occurred in offspring. Topiramate should be used during pregnancy only if the potential benefit outweighs the potential risk. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be informed of the potential hazard to the fetus.
• Pregnancy Registry

• Patients should be encouraged to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry if they become pregnant. This registry is collecting information about the safety of antiepileptic drugs during pregnancy. To enroll, patients can call the toll-free number 1-888-233-2334. Information about the North American Drug Pregnancy Registry can be found at http://www.massgeneral.org/aed/.

• Human Data

• Data from the NAAED Pregnancy Registry indicate an increased risk of oral clefts in infants exposed to topiramate monotherapy during the first trimester of pregnancy. The prevalence of oral clefts was 1.2% compared to a prevalence of 0.39% - 0.46% in infants exposed to other AEDs, and a prevalence of 0.12% in infants of mothers without epilepsy or treatment with other AEDs. For comparison, the Centers for Disease Control and Prevention (CDC) reviewed available data on oral clefts in the United States and found a similar background rate of 0.17%. The relative risk of oral clefts in topiramate-exposed pregnancies in the NAAED Pregnancy Registry was 9.6 (95% Confidence Interval=CI 3.6-25.7) as compared to the risk in a background population of untreated women. The UK Epilepsy and Pregnancy Register reported a similarly increased prevalence of oral clefts of 3.2% among infants exposed to topiramate monotherapy. The observed rate of oral clefts was 16 times higher than the background rate in the UK, which is approximately 0.2%.
• Topiramate treatment can cause metabolic acidosis [see Warnings and Precautions (5.4)]. The effect of topiramate-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) can cause decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus' ability to tolerate labor. Pregnant patients should be monitored for metabolic acidosis and treated as in the nonpregnant state [see Warnings and Precautions (5.4)]. Newborns of mothers treated with topiramate should be monitored for metabolic acidosis because of transfer of topiramate to the fetus and possible occurrence of transient metabolic acidosis following birth.

• Animal Data

• Topiramate has demonstrated selective developmental toxicity, including teratogenicity, in multiple animal species at clinically relevant doses. When oral doses of 20 mg/kg, 100 mg/kg, or 500 mg/kg were administered to pregnant mice during the period of organogenesis, the incidence of fetal malformations (primarily craniofacial defects) was increased at all doses. The low dose is approximately 0.2 times the recommended human dose (RHD) 400 mg per day on a mg/m2 basis. Fetal body weights and skeletal ossification were reduced at 500 mg/kg in conjunction with decreased maternal body weight gain.
• In rat studies (oral doses of 20 mg/kg, 100 mg/kg, and 500 mg/kg or 0.2 mg/kg, 2.5 mg/kg, 30 mg/kg, and 400 mg/kg), the frequency of limb malformations (ectrodactyly, micromelia, and amelia) was increased among the offspring of dams treated with 400 mg/kg (10 times the RHD on a mg/m2 basis) or greater during the organogenesis period of pregnancy. Embryotoxicity (reduced fetal body weights, increased incidence of structural variations) was observed at doses as low as 20 mg/kg (0.5 times the RHD on a mg/m2 basis). Clinical signs of maternal toxicity were seen at 400 mg/kg and above, and maternal body weight gain was reduced during treatment with 100 mg/kg or greater.
• In rabbit studies (20 mg/kg, 60 mg/kg, and 180 mg/kg or 10 mg/kg, 35 mg/kg, and 120 mg/kg orally during organogenesis), embryo/fetal mortality was increased at 35 mg/kg (2 times the RHD on a mg/m2 basis) or greater, and teratogenic effects (primarily rib and vertebral malformations) were observed at 120 mg/kg (6 times the RHD on a mg/m2 basis). Evidence of maternal toxicity (decreased body weight gain, clinical signs, and/or mortality) was seen at 35 mg/kg and above.
• When female rats were treated during the latter part of gestation and throughout lactation (0.2 mg/kg, 4 mg/kg, 20 mg/kg, and 100 mg/kg or 2, 20, and 200 mg/kg), offspring exhibited decreased viability and delayed physical development at 200 mg/kg (5 times the RHD on a mg/m2 basis) and reductions in pre-and/or postweaning body weight gain at 2 mg/kg (0.05 times the RHD on a mg/m2 basis) and above. Maternal toxicity (decreased body weight gain, clinical signs) was evident at 100 mg/kg or greater.
• In a rat embryo/fetal development study with a postnatal component (0.2 mg/kg, 2.5 mg/kg, 30 mg/kg, or 400 mg/kg during organogenesis; noted above), pups exhibited delayed physical development at 400 mg/kg (10 times the RHD on a mg/m2 basis) and persistent reductions in body weight gain at 30 mg/kg (1 times the RHD on a mg/m2 basis) and higher.

• Women of Childbearing Potential

• Data from pregnancy registries indicate that infants exposed to topiramate in utero have an increased risk for cleft lip and/or cleft palate (oral clefts) Consider the benefits and risks of topiramate when prescribing this drug to women of childbearing potential, particularly when topiramate is considered for a condition not usually associated with permanent injury or death. Because of the risk of oral clefts to the fetus, which occur in the first trimester of pregnancy before many women know they are pregnant, all women of childbearing potential should be apprised of the potential hazard to the fetus from exposure to topiramate. If the decision is made to use topiramate, women who are not planning a pregnancy should use effective contraception . Women who are planning a pregnancy should be counseled regarding the relative risks and benefits of topiramate use during pregnancy, and alternative therapeutic options should be considered for these patients.

Pregnancy Category (AUS): There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Topiramate in women who are pregnant.

Labor and Delivery

Although the effect of topiramate on labor and delivery in humans has not been established, the development of topiramate-induced metabolic acidosis in the mother and/or in the fetus might affect the fetus' ability to tolerate labor

Nursing Mothers

Limited data on 5 breastfeeding infants exposed to topiramate showed infant plasma topiramate levels equal to 10-20% of the maternal plasma level. The effects of this exposure on infants are unknown. Caution should be exercised when topiramate is administered to a nursing woman.

Pediatric Use

• Seizures in Pediatric Patients 2 Years of Age and Older
• The safety and effectiveness of QUDEXY XR in pediatric patients is based on controlled trials with immediate-release topiramate
• The adverse reactions (both common and serious) in pediatric patients are similar to those seen in adults
• These include, but are not limited to:

• Oligohydrosis and hyperthermia
• Dose-related increased incidence of metabolic acidosis
• Dose-related increased incidence of hyperammonemia
• Adjunctive Treatment for Epilepsy with Partial Onset Seizures in Infants and Toddlers (1 to 24 months)

• The following pediatric use information is based on studies conducted with immediate-release topiramate.

• Safety and effectiveness in patients below the age of 2 years have not been established for the adjunctive therapy treatment of partial onset seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox-Gastaut syndrome. In a single randomized, double-blind, placebo-controlled investigational trial, the efficacy, safety, and tolerability of immediate-release topiramate oral liquid and sprinkle formulations as an adjunct to concurrent antiepileptic drug therapy in infants 1 to 24 months of age with refractory partial onset seizures, was assessed. After 20 days of double-blind treatment, immediate-release topiramate (at fixed doses of 5 mg/kg, 15 mg/kg, and 25 mg/kg per day) did not demonstrate efficacy compared with placebo in controlling seizures.

• In general, the adverse reaction profile in this population was similar to that of older pediatric patients, although results from the above controlled study, and an open-label, long-term extension study in these infants/toddlers (1 to 24 months old) suggested some adverse reactions not previously observed in older pediatric patients and adults; i.e., growth/length retardation, certain clinical laboratory abnormalities, and other adverse reactions that occurred with a greater frequency and/or greater severity than had been recognized previously from studies in older pediatric patients or adults for various indications.
• These very young pediatric patients appeared to experience an increased risk for infections (any topiramate dose 12%, placebo 0%) and of respiratory disorders (any topiramate dose 40%, placebo 16%). The following adverse reactions were observed in at least 3% of patients on immediate-release topiramate and were 3% to 7% more frequent than in patients on placebo: viral infection, bronchitis, pharyngitis, rhinitis, otitis media, upper respiratory infection, cough, and bronchospasm. A generally similar profile was observed in older children
• Immediate-release topiramate resulted in an increased incidence of patients with increased creatinine (any topiramate dose 5%, placebo 0%), BUN (any topiramate dose 3%, placebo 0%), and protein (any topiramate dose 34%, placebo 6%), and an increased incidence of decreased potassium (any topiramate dose 7%, placebo 0%). This increased frequency of abnormal values was not dose related. Creatinine was the only analyte showing a noteworthy increased incidence (topiramate 25 mg/kg/day 5%, placebo 0%) of a markedly abnormal increase. The significance of these findings is uncertain.
• Immediate-release topiramate treatment also produced a dose-related increase in the percentage of patients who had a shift from normal at baseline to high/increased (above the normal reference range) in total eosinophil count at the end of treatment. The incidence of these abnormal shifts was 6 % for placebo, 10% for 5 mg/kg/day, 9% for 15 mg/kg/day, 14% for 25 mg/kg/day, and 11% for any topiramate dose. There was a mean dose-related increase in alkaline phosphatase. The significance of these findings is uncertain.
• Treatment with immediate-release topiramate for up to 1 year was associated with reductions in Z SCORES for length, weight, and head circumference.
• In open-label, uncontrolled experience, increasing impairment of adaptive behavior was documented in behavioral testing over time in this population. There was a suggestion that this effect was dose-related. However, because of the absence of an appropriate control group, it is not known if this decrement in function was treatment related or reflects the patient's underlying disease (e.g., patients who received higher doses may have more severe underlying disease).
• In this open-label, uncontrolled study, the mortality was 37 deaths/1000 patient years. It is not possible to know whether this mortality rate is related to immediate-release topiramate treatment, because the background mortality rate for a similar, significantly refractory, young pediatric population (1 month to 24 months) with partial epilepsy is not known.
• Other Pediatric Studies

• Topiramate treatment produced a dose-related increased shift in serum creatinine from normal at baseline to an increased value at the end of 4 months treatment in adolescent patients (ages 12 years to 16 years) in a double-blind, placebo-controlled study.

• Juvenile Animal Studies

• When topiramate (30 mg/kg/day, 90 mg/kg/day or 300 mg/kg/day) was administered orally to rats during the juvenile period of development (postnatal days 12 to 50), bone growth plate thickness was reduced in males at the highest dose, which is approximately 5 to 8 times the maximum recommended pediatric dose (9 mg/kg/day) on a body surface area (mg/m2) basis.

Geriatic Use

Clinical studies of immediate-release topiramate did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. Dosage adjustment is necessary for elderly with creatinine clearance less than 70 mL/min/1.73 m2. Estimate CrCl prior to dosing

Gender

Evaluation of effectiveness and safety of topiramate in clinical trials has shown no race- or gender-related effects.

Race

There is no FDA guidance on the use of Topiramate with respect to specific racial populations.

Renal Impairment

The clearance of topiramate was reduced by 42% in moderately renally impaired (creatinine clearance 30 to 69 mL/min/1.73m2) and by 54% in severely renally impaired subjects (creatinine clearance less than 30 mL/min/1.73m2) compared to normal renal function subjects (creatinine clearance greater than 70 mL/min/1.73m2). One-half the usual starting and maintenance dose is recommended in patients with moderate or severe renal impairment

Hepatic Impairment

There is no FDA guidance on the use of Topiramate in patients with hepatic impairment.

Females of Reproductive Potential and Males

There is no FDA guidance on the use of Topiramate in women of reproductive potentials and males.

Immunocompromised Patients

There is no FDA guidance one the use of Topiramate in patients who are immunocompromised.

Patients Undergoing Hemodialysis

Topiramate is cleared by hemodialysis at a rate that is 4 to 6 times greater than a normal individual. Accordingly, a prolonged period of dialysis may cause topiramate concentration to fall below that required to maintain an anti-seizure effect. To avoid rapid drops in topiramate plasma concentration during hemodialysis, a supplemental dose of topiramate may be required. The actual adjustment should take into account the duration of dialysis period, the clearance rate of the dialysis system being used, and the effective renal clearance of topiramate in the patient being dialyzed

Administration and Monitoring

Administration

There is limited information regarding Topiramate Administration in the drug label.

Monitoring

There is limited information regarding Topiramate Monitoring in the drug label.

IV Compatibility

There is limited information regarding the compatibility of Topiramate and IV administrations.

Overdosage

• Overdoses of topiramate resulted in signs and symptoms which included convulsions, drowsiness, speech disturbance, blurred vision, diplopia, mentation impaired, lethargy, abnormal coordination, stupor, hypotension, abdominal pain, agitation, dizziness and depression. The clinical consequences were not severe in most cases, but deaths have been reported after polydrug overdoses involving topiramate.
• Topiramate overdose has resulted in severe metabolic acidosis.
• A patient who ingested a dose between 96 g and 110 g of topiramate was admitted to hospital with coma lasting 20 to 24 hours followed by full recovery after 3 to 4 days.
• Similar signs, symptoms, and clinical consequences are expected to occur with overdosage of topiramate. Therefore, in acute topiramate overdose, if the ingestion is recent, the stomach should be emptied immediately by lavage or by induction of emesis. Activated charcoal has been shown to adsorb topiramate in vitro. Treatment should be appropriately supportive. Hemodialysis is an effective means of removing topiramate from the body.

Pharmacology

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Topiramate
Systematic (IUPAC) name
2,3:4,5-Bis-O-(1-methylethylidene)-beta-D-fructopyranose sulfamate
Identifiers
CAS number	97240-79-4
ATC code	N03AX11
PubChem	5284627
DrugBank	DB00273
Chemical data
Formula	Template:OrganicBox atomTemplate:OrganicBox atomTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBox atomTemplate:OrganicBoxTemplate:OrganicBox atomTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBox atomTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBoxTemplate:OrganicBox
Mol. mass	339.363 g/mol
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	80%
Protein binding	13-17%; 15-41%
Metabolism	Hepatic (20-30%)
Half life	19-25 hours
Excretion	Urine (70-80%)
Therapeutic considerations
Licence data	US
Pregnancy cat.	D(AU) D(US)
Legal status	Prescription Only (S4)(AU) ?(CA) POM(UK) [[Prescription drug|Template:Unicode-only]](US)
Routes	Oral

Mechanism of Action

There is limited information regarding Topiramate Mechanism of Action in the drug label.

Structure

• Topiramate, USP, is a sulfamate-substituted monosaccharide. topiramate (topiramate) extended-release capsules are available as 25 mg, 50 mg, 100 mg, 150 mg, and 200 mg capsules for oral administration as whole capsules or opened and sprinkled onto a spoonful of soft food.
• Topiramate is a white to off-white powder. Topiramate is freely soluble in polar organic solvents such as acetonitrile and acetone; and very slightly soluble to practically insoluble in non-polar organic solvents such as hexanes. Topiramate has the molecular formula C12H21NO8S and a molecular weight of 339.4. Topiramate is designated chemically as 2,3:4,5-Di-O-isopropylidene-β-D-fructopyranose sulfamate and has the following structural formula:

This image is provided by the National Library of Medicine.

• Topiramate (topiramate) extended-release capsules contain beads of topiramate in a capsule. The inactive ingredients are microcrystalline cellulose, hypromellose 2910, ethylcellulose, diethyl phthalate.
• In addition, the capsule shells for all strengths contain hypromellose 2910, titanium dioxide, black iron oxide, red iron oxide and/or yellow iron oxide, black pharmaceutical ink, and white pharmaceutical ink (200 mg only).

Pharmacodynamics

There is limited information regarding Topiramate Pharmacodynamics in the drug label.

Pharmacokinetics

There is limited information regarding Topiramate Pharmacokinetics in the drug label.

Nonclinical Toxicology

• Carcinogenesis

• An increase in urinary bladder tumors was observed in mice given topiramate (20 mg/kg, 75 mg/kg, and 300 mg/kg) in the diet for 21 months. The elevated bladder tumor incidence, which was statistically significant in males and females receiving 300 mg/kg, was primarily due to the increased occurrence of a smooth muscle tumor considered histomorphologically unique to mice. Plasma exposures in mice receiving 300 mg/kg were approximately 0.5 to 1 times steady-state exposures measured in patients receiving topiramate monotherapy at the recommended human dose (RHD) of 400 mg, and 1.5 to 2 times steady-state topiramate exposures in patients receiving 400 mg of topiramate plus phenytoin. The relevance of this finding to human carcinogenic risk is uncertain.

• No evidence of carcinogenicity was seen in rats following oral administration of topiramate for 2 years at doses up to 120 mg/kg (approximately 3 times the RHD on a mg/m2 basis).
• Mutagenesis

• Topiramate did not demonstrate genotoxic potential when tested in a battery of in vitro and in vivo assays. Topiramate was not mutagenic in the Ames test or the in vitro mouse lymphoma assay; it did not increase unscheduled DNA synthesis in rat hepatocytes in vitro; and it did not increase chromosomal aberrations in human lymphocytes in vitro or in rat bone marrow in vivo.

• Impairment of Fertility

• No adverse effects on male or female fertility were observed in rats at doses up to 100 mg/kg (2.5 times the RHD on a mg/m2 basis).

Clinical Studies

There is limited information regarding Topiramate Clinical Studies in the drug label.

How Supplied

There is limited information regarding Topiramate How Supplied in the drug label.

Storage

There is limited information regarding Topiramate Storage in the drug label.

Images

Drug Images

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Patient Counseling Information

There is limited information regarding Topiramate Patient Counseling Information in the drug label.

Precautions with Alcohol

Alcohol-Topiramate interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication.

Brand Names

There is limited information regarding Topiramate Brand Names in the drug label.

Look-Alike Drug Names

There is limited information regarding Topiramate Look-Alike Drug Names in the drug label.

Drug Shortage Status

Price

References

The contents of this FDA label are provided by the National Library of Medicine.