Topiramate

Pronunciation

Class: Anticonvulsants, Miscellaneous
VA Class: CN400
Chemical Name: 2,3:4,5-bis-O-(1-Methylethylidene)-β-d-fructopyranose sulfamate
Molecular Formula: C12H21NO8S
CAS Number: 97240-79-4
Brands: Topamax

Warning(s)

Special Alerts:

[Posted 03/04/2011] ISSUE: FDA notified healthcare professionals and patients of an increased risk of development of cleft lip and/or cleft palate (oral clefts) in infants born to women treated with topiramate (Topamax) during pregnancy. Because of new human data that show an increased risk for oral clefts, topiramate is being placed in Pregnancy Category D. Pregnancy Category D means there is positive evidence of human fetal risk based on human data but the potential benefits from use of the drug in pregnant women may be acceptable in certain situations despite its risks. The patient medication guide and prescribing information for Topamax and generic topiramate will be updated with the new information.

BACKGROUND: Topiramate is an anticonvulsant medication approved for use alone or with other medications to treat patients with epilepsy who have certain types of seizures. Topiramate is also approved for use to prevent migraine headaches. The new data was from the North American Antiepileptic Drug (NAAED) Pregnancy Registry.

RECOMMENDATION: Before starting topiramate, pregnant women and women of childbearing potential should discuss other treatment options with their health care professional. Women taking topiramate should tell their health care professional immediately if they are planning to or become pregnant. Patients taking topiramate should not stop taking it unless told to do so by their health care professional. Women who become pregnant while taking topiramate should talk to their health care professional about registering with the North American Antiepileptic Drug Pregnancy Registry, a group that collects information about outcomes in infants born to women treated with antiepileptic drugs during pregnancy. For more information visit the FDA website at: and .

[UPDATE 05/05/2009] FDA notified healthcare professionals that it approved updated labeling for antiepileptic drugs used to treat epilepsy, psychiatric disorders, and other conditions (e.g., migraine and neuropathic pain syndromes). FDA also required development of a medication guide, to be issued to patients each time the product is dispensed. Since issuing safety alerts on December 16, 2008 and January 31, 2008, FDA has been working with the manufacturers of drugs in this class to better understand the suicidality risk. Eleven antiepileptic drugs were included in a pooled analysis of placebo-controlled clinical studies in which these drugs were used to treat epilepsy as well as psychiatric disorders and other conditions. The increased risk of suicidal thoughts or behavior was generally consistent among the eleven drugs, with varying mechanisms of action and across a range of indications. This observation suggests that the risk applies to all antiepileptic drugs used for any indication.

The drugs included in the analyses include (some of these drugs are also available in generic form):

  • Carbamazepine (marketed as Carbatrol, Equetro, Tegretol, Tegretol XR)

  • Felbamate (marketed as Felbatol)

  • Gabapentin (marketed as Neurontin)

  • Lamotrigine (marketed as Lamictal)

  • Levetiracetam (marketed as Keppra)

  • Oxcarbazepine (marketed as Trileptal)

  • Pregabalin (marketed as Lyrica)

  • Tiagabine (marketed as Gabitril)

  • Topiramate (marketed as Topamax)

  • Valproate (marketed as Depakote, Depakote ER, Depakene, Depacon)

  • Zonisamide (marketed as Zonegran)

For more information visit the FDA website at: and .

[UPDATE 12/16/2008] The FDA has completed its analysis of reports of suicidality (suicidal behavior or ideation [thoughts]) from placebo-controlled clinical trials of drugs used to treat epilepsy, psychiatric disorders, and other conditions. Based on the outcome of this review, FDA is requiring that all manufacturers of drugs in this class include a Warning in their labeling and develop a Medication Guide to be provided to patients prescribed these drugs to inform them of the risks of suicidal thoughts or actions.

For more information visit the FDA website at: and .

[Posted 01/31/2008] FDA informed healthcare professionals that the Agency has analyzed reports of suicidality (suicidal behavior or ideation) from placebo-controlled clinical studies of eleven drugs used to treat epilepsy as well as psychiatric disorders, and other conditions. In the FDA’s analysis, patients receiving antiepileptic drugs had approximately twice the risk of suicidal behavior or ideation (0.43%) compared to patients receiving placebo (0.22%). The increased risk of suicidal behavior and suicidal ideation was observed as early as one week after starting the antiepileptic drug and continued through 24 weeks. The results were generally consistent among the eleven drugs. The relative risk for suicidality was higher in patients with epilepsy compared to patients who were given one of the drugs in the class for psychiatric or other conditions.

Healthcare professionals should closely monitor all patients currently taking or starting any antiepileptic drug for notable changes in behavior that could indicate the emergence or worsening of suicidal thoughts or behavior or depression.

The drugs included in the analyses include (some of these drugs are also available in generic form):

  • Carbamazepine (marketed as Carbatrol, Equetro, Tegretol, Tegretol XR)

  • Felbamate (marketed as Felbatol)

  • Gabapentin (marketed as Neurontin)

  • Lamotrigine (marketed as Lamictal)

  • Levetiracetam (marketed as Keppra)

  • Oxcarbazepine (marketed as Trileptal)

  • Pregabalin (marketed as Lyrica)

  • Tiagabine (marketed as Gabitril)

  • Topiramate (marketed as Topamax)

  • Valproate (marketed as Depakote, Depakote ER, Depakene, Depacon)

  • Zonisamide (marketed as Zonegran)

Although the 11 drugs listed above were the ones included in the analysis, FDA expects that the increased risk of suicidality is shared by all antiepileptic drugs and anticipates that the class labeling changes will be applied broadly. For more information visit the FDA website at: and .

REMS:

FDA approved a REMS for topiramate to ensure that the benefits of a drug outweigh the risks. However, FDA later rescinded REMS requirements. See the FDA REMS page () or the ASHP REMS Resource Center ().

Introduction

Anticonvulsant and antimigraine agent; sulfamate-substituted derivative ofd-fructose;1 2 3 4 5 17 18 differs structurally from other currently available anticonvulsant agents.1 2 3 4 5 17 18

Uses for Topiramate

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Seizure Disorders

Management (in combination with other anticonvulsants) of partial seizures in adults and children 2–16 years of age.1 2 4 5 6 7 8 9 10 22 25 29 30 31 32 33 34 37 38

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Management (in combination with other anticonvulsants) of primary generalized tonic-clonic seizures in adults and children 2–16 years of age.1 30 31 39

Management (in combination with other anticonvulsants) of seizures associated with Lennox-Gastaut syndrome in adults and children ≥2 years of age.1

Migraine Prophylaxis

Prophylaxis of migraine headache in adults.1

Efficacy in the acute management (i.e., abortive therapy) of migraine headache not established.1

Topiramate Dosage and Administration

General

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

  • Monitoring of plasma topiramate concentrations is not necessary when topiramate is added to an existing anticonvulsant regimen; however, addition of topiramate to phenytoin therapy may require adjustment of phenytoin dosage.1 2 4

  • Addition or withdrawal of phenytoin and/or carbamazepine during adjunctive therapy may require adjustment of topiramate dosage.1 2 4 11 (See Specific Drugs under Interactions.)

  • Adjust dosage carefully and individualize according to patient response and tolerance.1 2 4

  • Too rapid titration (e.g., over 3–6 weeks) to achieve target dosage and/or excessive target dosage may contribute to a higher incidence of adverse effects.1 2 4

Administration

Oral Administration

Administer orally without regard to meals.1 2 4

Capsule/sprinkle formulation is bioequivalent to immediate-release tablet and may be substituted as a therapeutic equivalent.1

Capsules

Swallow capsules whole.1

Alternatively, open capsule and sprinkle entire contents on soft food (e.g., applesauce, custard, ice cream, oatmeal, yogurt, pudding); swallow immediately without chewing.1

Drinking fluids immediately may help to ensure that all of the mixture is swallowed.1

Do not store the sprinkle/food mixture for use at a later time.1

Tablets

Tablets preferably should be swallowed intact and not broken or chewed because of the bitter taste.1 2 4 24

If patient has difficulty in swallowing tablets, the tablets may be crushed and mixed with oatmeal or applesauce; use immediately since stability cannot be ensured.24

If tablets are broken, use immediately since stability beyond a brief period cannot be ensured.24 Discard any unused portion.24

Dosage

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Pediatric Patients

Seizure Disorders
Partial Seizures, Primary Generalized Tonic-Clonic Seizures, or Seizures Associated with Lennox-Gastaut Syndrome
Oral

Initially, 25 mg (or less based on a range of 1–3 mg/kg daily) given nightly for the first week in children 2–16 years of age.1 Increase dosage at 1- or 2-week intervals in increments of 1–3 mg/kg daily, administered in 2 divided doses, to achieve optimal clinical response.1

Maintenance, 5–9 mg/kg daily in 2 divided doses.1

Alternatively, some clinicians recommend an initial dosage of 0.5–1 mg/kg daily, with slow titration (in increments of 1–3 mg/kg every other week or in increments of 0.5–1 mg/kg per week) to obtain optimal efficacy with minimal adverse effects.33 36

Adults

Seizure Disorders
Partial Seizures
Oral

Initially, 25–50 mg daily.1 2 4 24 Increase dosage at weekly intervals in increments of 25–50 mg to achieve optimal clinical response.1 2 4 24

Recommended maintenance dosage is 200–400 mg daily, administered in 2 equally divided doses (morning and evening).1 2 4 24

Titration in increments of 25 mg/week is associated with a lower incidence of cognitive and psychiatric adverse effects and lower discontinuance rates24 41 but may delay the time to reach an effective dosage.1 24 41

Dosages >400 mg daily generally have not produced substantial additional improvement, but may improve seizure control in some patients, if tolerated.1 2 4 7 24 25

Primary Generalized Tonic-Clonic Seizures
Oral

Initially, 25–50 mg daily.1 2 4 24 Increase dosage at weekly intervals in increments of 25–50 mg to achieve optimal clinical response.1 2 4 24

Recommended maintenance dosage is 400 mg daily, administered in 2 equally divided doses (morning and evening).1 2 4 24

Titration in increments of 25 mg/week is associated with a lower incidence of cognitive and psychiatric adverse effects and lower discontinuance rates24 41 but may delay the time to reach an effective dosage.1 24 41

Seizures Associated with Lennox-Gastaut Syndrome
Oral

Manufacturer makes no specific dosage recommendations; in 1 controlled trial, topiramate was initiated at dosage of 1 mg/kg and titrated over 2 weeks to target dosage of approximately 6 mg/kg daily.1 24

Migraine Prophylaxis
Oral

Recommended total daily dosage is 100 mg, administered in 2 divided doses.1 Titrate therapy using the following schedule in Table 1.

Table 1. Topiramate Dosage Titration Schedule for Migraine Prophylaxis in Adults

Week

Morning Dose

Evening Dose

1

None

25 mg

2

25 mg

25 mg

3

25 mg

50 mg

4

50 mg

50 mg

Titrate dosage based on clinical outcome.1 Use longer intervals between dose adjustments if required.1

Prescribing Limits

Adults

Seizure Disorders
Oral

Dosages >1.6 g daily in patients with seizure disorders have not been studied.1 2 4

Special Populations

Hepatic Impairment

Clearance may be decreased; however, manufacturer makes no specific recommendations regarding dosage adjustment.1

Renal Impairment

If Clcr is <70 mL/minute per 1.73 m2, decrease daily adult dosage by 50%.1 2 4 Patients with renal impairment will require a longer time to reach steady state at each dosage level.1 2 4

Patients undergoing hemodialysis may require a supplemental dose following dialysis session; base amount on duration of dialysis, clearance rate of dialysis system, and the patient’s effective renal clearance of topiramate.1 2 4

Geriatric Patients

If Clcr <70 mL/minute per 1.73 m2, dosage adjustment may be necessary.1 (See Renal Impairment under Dosage and Administration.)

Cautions for Topiramate

Contraindications

  • Known hypersensitivity to topiramate or any ingredient in the formulation.1

Warnings/Precautions

Warnings

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Metabolic Acidosis

Hyperchloremic, non-anion gap, metabolic acidosis reported.1 43 (See Pediatric Use under Cautions.) Possible hyperventilation, nonspecific symptoms (e.g., fatigue, anorexia), cardiac arrhythmias, or stupor.1 43 Generally occurs early in therapy but can occur at any time.1 43

Potential for serious sequelae (e.g., nephrolithiasis, nephrocalcinosis, osteomalacia and/or osteoporosis with increased risk for fractures) resulting from chronic, untreated metabolic acidosis.1 43

Measure serum bicarbonate concentrations at baseline and periodically during therapy.1 43

If metabolic acidosis develops and persists, consider reducing dosage or discontinuing therapy (by gradually tapering dose).1 43 If therapy is continued in patient with persistent acidosis, consider alkali treatment.1 43

Cognitive/Neuropsychiatric Effects

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Confusion, psychomotor slowing, difficulty with concentration/attention, difficulty with memory, speech or language problems (e.g., word-finding difficulties), psychiatric/behavioral disturbances (e.g., depression, mood problems), somnolence, and fatigue associated with use in adults.1

Psychomotor slowing, difficulty with concentration/attention, speech disorders/related speech problems, and language problems associated with use in children 2–16 years of age; incidence of these effects is lower in children than in adults.1

Withdrawal Seizures

Discontinue drug gradually to minimize the potential for increased seizure frequency.1

Ocular Effects

Acute myopia with secondary angle-closure glaucoma reported.1 Symptoms (e.g., acute onset of decreased visual acuity and/or ocular pain) typically occur within 1 month of initiating therapy.1

If adverse ocular signs or symptoms are detected, discontinue topiramate immediately and institute appropriate measures.1

Oligohidrosis and Hyperthermia

Possible oligohidrosis and hyperthermia, particularly in pediatric patients; rarely may require hospitalization.1 42

Monitor patients, particularly pediatric patients, closely for decreased sweating and increased body temperature, particularly in warm or hot weather.1 Ensure proper hydration before and during exercise or exposure to warm temperatures.42

Consider risk of hyperthermia when used concomitantly with other drugs that predispose to heat-related disorders.1 (See Drugs Predisposing to Heat-related Disorders under Interactions.)

Sudden, Unexplained Deaths in Epilepsy

Higher incidence of sudden and unexplained deaths than would be expected in a healthy (nonepileptic) population; however, incidence is within range of estimates for patients with epilepsy or refractory epilepsy.1

General Precautions

Hyperammonemia

Hyperammonemia, with or without encephalopathy, reported following concomitant use with valproic acid.1

Manifestations of hyperammonemic encephalopathy include acute alterations in level of consciousness and/or cognitive function with lethargy or vomiting.1 In most cases, manifestations abated following discontinuance of either topiramate or valproic acid.1

If unexplained lethargy, vomiting, or changes in mental status occur, consider possibility of hyperammonemic encephalopathy and measure ammonia concentration.1

Kidney Stones

Increased incidence (1.5%) of kidney stone formation in clinical trials in adults; incidence higher in men than women.1 Kidney stones also reported in children 2–16 years of age.1

Avoid use in patients receiving other carbonic anhydrase inhibitors and in those on ketogenic diet.1

Maintain adequate fluid intake to decrease stone formation.1

Paresthesia

Common adverse effect; often associated with other carbonic anhydrase inhibitors.1

Possible Prescribing and Dispensing Errors

Ensure accuracy of prescription; similarity in spelling between Topamax (topiramate) and Toprol-XL (a trade name for metoprolol succinate, a β-adrenergic blocking agent) may result in errors.47 48 49 50 These medication errors have been associated with serious adverse events sometimes requiring hospitalization as a result of either lack of the intended medication (e.g., seizure or hypertension recurrence) or exposure to the wrong drug (e.g., bradycardia in a patient erroneously receiving metoprolol).47 48 49 50

Specific Populations

Pregnancy

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

Category C.1

Lactation

Distributed into milk in rats; limited data suggest that drug may be distributed extensively into milk in humans.1 Use only if potential benefits outweigh the risks.1

Pediatric Use

Safety and efficacy for management of seizure disorders not established in children <2 years of age.1 2 Safety and efficacy for migraine prophylaxis not established in pediatric patients.1

Hyperchloremic, non-anion gap, metabolic acidosis reported.1 43 (See Metabolic Acidosis under Cautions.)

Decreases in serum bicarbonate concentrations reported in 67 or 10% of pediatric patients receiving topiramate (approximately 6 mg/kg daily) or placebo, respectively.1 43

Cases of moderately severe metabolic acidosis reported in infants as young as 5 months of age, especially at dosages >5 mg/kg daily.1 Potential for serious sequelae (e.g., osteomalacia [rickets], reduced growth rates, decrease in maximal height achieved) resulting from chronic, untreated metabolic acidosis.1 43

Measure serum bicarbonate concentrations at baseline and periodically during therapy.1 43

Incidence of adverse nervous system effects appears to be lower in children than adults.1

Oligohydrosis and hyperthermia typically reported in children.1 42 (See Oligohidrosis and Hyperthermia under Cautions.)

Geriatric Use

Insufficient experience in patients ≥65 years of age to determine whether geriatric patients respond differently than younger patients.1

Clearance may be decreased in patients with reduced renal function.1 2 (See Special Populations under Pharmacokinetics.) Monitor renal function.1

Dosage adjustment may be necessary in geriatric patients with impaired renal function.1 (See Special Populations under Dosage and Administration.)

Hepatic Impairment

Clearance may be decreased; use with caution.1

Renal Impairment

Clearance decreased; dosage adjustment recommended for adults.1 (See Renal Impairment under Dosage and Administration.)

Common Adverse Effects

Adults receiving dosages of 50–200 mg daily (for migraine prophylaxis): paresthesia, fatigue, infection, taste perversion, nausea, anorexia, diarrhea, dizziness, weight loss, somnolence, difficulty with memory, difficulty with concentration/attention, sinusitis.1

Adults receiving dosages of 200–400 mg daily (for management of seizure disorders): somnolence, dizziness, ataxia, speech disorders and related speech problems, psychomotor slowing, abnormal vision, difficulty with memory, paresthesia, diplopia.1

Adults receiving dosages of 200–1000 mg daily (for management of seizure disorders): fatigue, nervousness, difficulty with concentration or attention, confusion, depression, anorexia, language problems, anxiety, mood problems, weight loss.1

Children 2–16 years of age receiving dosages of 5–9 mg/kg daily (for management of seizure disorders): fatigue, somnolence, anorexia, nervousness, difficulty with concentration/attention, difficulty with memory, aggressive reaction, weight loss.1

Interactions for Topiramate

Does not inhibit CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, or 3A4/5.1

Drugs Predisposing to Heat-related Disorders

Potential pharmacologic interaction (increased risk of hyperthermia) with drugs that predispose to heat-related disorders (e.g., carbonic anhydrase inhibitors, drugs with anticholinergic activity); use with caution.1

Specific Drugs

Drug

Interaction

Comments

Amitriptyline

Increased plasma amitriptyline concentrations1

Adjust amitriptyline dosage based on patient’s clinical response, not on plasma amitriptyline concentrations1

Carbamazepine

Decreased plasma concentrations of topiramate1

Carbonic anhydrase inhibitors (e.g., acetazolamide, dichlorphenamide)

Possible increased risk of kidney stone formation; possible increased risk of hyperthermia1

Avoid concomitant use1

CNS depressants (including alcohol)

Enhanced CNS depression1

Use with extreme caution1

Digoxin

Possible decrease in serum digoxin concentrations1

Clinical significance unknown1

Dihydroergotamine

Pharmacokinetic interaction unlikely1

Haloperidol

No effect on pharmacokinetics of haloperidol1

Lamotrigine

Increased plasma topiramate concentrations1

Lithium

Decreased plasma lithium concentrations1

Metformin

Possible increase in plasma metformin concentrations;1 possible decrease in topiramate clearance1

Clinical significance unknown; monitor blood glucose control carefully when topiramate is added or discontinued in patients receiving metformin1

Oral contraceptives

Decrease in ethinyl estradiol concentrations reported in patients also receiving valproic acid, resulting in potential decrease in oral contraceptive efficacy and possible breakthrough bleeding 1

Phenytoin

Possible increase in serum phenytoin concentrations (generally in those receiving twice-daily phenytoin regimen); decreased plasma topiramate concentrations1

Propranolol

Pharmacokinetic interaction unlikely1

Risperidone

Decreased plasma risperidone concentrations1

Closely monitor clinical response1

Sumatriptan

No effect on pharmacokinetics of sumatriptan1

Valproic acid

Possible decrease in plasma concentrations of valproic acid and topiramate; possible hyperammonemia with or without encephalopathy (see Hyperammonemia under Cautions)1

Topiramate Pharmacokinetics

Absorption

Bioavailability

Rapidly absorbed following oral administration, with peak plasma concentrations achieved in about 2 hours.1

Capsule/sprinkle formulation is bioequivalent to immediate-release tablet.1

Food

Food does not affect bioavailability.1 46

Distribution

Extent

Appears to cross the placenta.45

Distributes into breast milk.45

Plasma Protein Binding

Approximately 15–41%.1 Fraction bound decreases with increasing plasma topiramate concentrations.1

Elimination

Metabolism

Not extensively metabolized.1 Six minor metabolites identified; none constitutes more than 5% of administered dose.1

Elimination Route

Eliminated principally in urine as unchanged drug (approximately 70%).1

Half-life

21 hours.1 46

Special Populations

In pediatric patients, clearance is 50% higher, resulting in a shorter elimination half-life and lower plasma concentrations, relative to adults.1

In geriatric patients with reduced renal function (Clcr reduced by 20% compared with younger adults), clearance was decreased.1 1

In patients with hepatic impairment, clearance may be decreased; mechanism not fully understood.1

In patients with moderate or severe renal impairment, clearance is reduced by 42 or 54%, respectively.1 In patients undergoing hemodialysis, clearance is 4–6 times more rapid than in healthy individuals.1 2 4

Stability

Storage

Oral

Capsules

Tight containers at ≤25° C.1 Protect from moisture.1

Tablets

Tight containers at 15–30° C.1 Protect from moisture.1

Actions

  • Mechanism of action is unknown; however, properties that may contribute to anticonvulsant and antimigraine activities, including blocking sodium channels, enhancing the inhibitory action of GABA by acting at some subtypes of GABA-A receptor, antagonizing AMPA/kainate subtype of glutamate receptor, and inhibiting carbonic anhydrase enzymes have been demonstrated in electrophysiologic and biochemical studies.1 2 4 15 16 17 18 19

Advice to Patients

Pending revision, the material in this section should be considered in light of more recently available information in the MedWatch notification at the beginning of this monograph.

  • Importance of taking topiramate exactly as prescribed.1 Importance of not abruptly discontinuing therapy.1

  • Importance of seeking immediate medical attention if blurred vision or periorbial pain develops.1

  • Importance of maintaining adequate fluid intake, particularly in patients with predisposing factors, to minimize the risk of kidney stone formation.1

  • Importance of considering an increase in food intake if patient is losing weight while taking topiramate.1

  • Importance of reviewing the manufacturer’s patient information for instructions regarding administration of the capsule/sprinkle formulation.1

  • Potential for drug to impair mental alertness or physical coordination; avoid driving or operating machinery until effects on individual are known.1

  • Importance of monitoring for evidence of decreased sweating and increased body temperature, particularly in children during hot weather.1 42 Importance of proper hydration before and during exercise and exposure to warm temperatures.42

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.1

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.1

  • Importance of informing patients of other important precautionary information.1 (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Topiramate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Capsules

15 mg

Topamax Sprinkle (with povidone)

Ortho-McNeil

25 mg

Topamax Sprinkle (with povidone)

Ortho-McNeil

Tablets, film-coated

25 mg

Topamax

Ortho-McNeil

50 mg

Topamax

Ortho-McNeil

100 mg

Topamax

Ortho-McNeil

200 mg

Topamax

Ortho-McNeil

Comparative Pricing

This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 02/2014. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.

Topamax 100MG Tablets (JANSSEN): 60/$556.01 or 180/$1,650.05

Topamax 200MG Tablets (JANSSEN): 60/$626.00 or 180/$1,790.90

Topamax 25MG Tablets (JANSSEN): 60/$201.99 or 180/$574.97

Topamax 50MG Tablets (JANSSEN): 60/$400.01 or 180/$1,119.96

Topiramate 100MG Tablets (GLENMARK PHARMACEUTICALS): 60/$49.99 or 180/$129.98

Topiramate 15MG Sprinkle Capsules (TEVA PHARMACEUTICALS USA): 60/$70.99 or 180/$199.96

Topiramate 200MG Tablets (GLENMARK PHARMACEUTICALS): 60/$50.99 or 180/$130.97

Topiramate 25MG Sprinkle Capsules (TEVA PHARMACEUTICALS USA): 60/$85.99 or 180/$235.96

Topiramate 25MG Tablets (GLENMARK PHARMACEUTICALS): 60/$29.99 or 180/$79.97

Topiramate 50MG Tablets (GLENMARK PHARMACEUTICALS): 60/$39.99 or 180/$99.97

AHFS DI Essentials. © Copyright, 2004-2014, Selected Revisions October 27, 2011. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

References

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2. Ortho-McNeil. Topamax (topiramate) clinical review. Raritan, NJ: undated.

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4. Ortho-McNeil. Topamax (topiramate) tablets product information reference source. Raritan, NJ; 1997 Jan.

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6. Faught E, Wilder BJ, Ramsay RE et al et al. Topiramate placebo-controlled dose-ranging trial in refractory partial epilepsy using 200-, 400-, and 600-mg daily dosages. Neurology. 1996; 46:1684-90. [IDIS 368533] [PubMed 8649570]

7. Privitera M, Fincham R, Penry J et al et al. Topiramate placebo-controlled dose-ranging trial in refractory partial epilepsy using 600-, 800-, and 1,000-mg daily dosages. Neurology. 1996; 46:1678-83. [IDIS 368532] [PubMed 8649569]

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11. Bourgeois BFD. Drug interaction profile of topiramate. Epilepsia. 1996; 37(Suppl 2):S14-17.

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13. Membrane potentials and action potentials. In: Guyton AC. Textbook of medical physiology. 8th ed. Philadelphia: WB Saunders; 1991:51-66.

14. Lipton SA, Rosenberg PA. Excitatory amino acids as a final common pathway for neurologic disorders. N Engl J Med. 1994; 330:613-22. [IDIS 326265] [PubMed 7905600]

15. Dichter MA, Brodie MJ. New antiepileptic drugs. N Engl J Med. 1996; 334:1583-90. [IDIS 366423] [PubMed 8628341]

16. White HS, Brown SD, Wolf HH et al. The anticonvulsant topiramate potentiates GABA-evoked chloride current in mouse cortical neurons. Epilepsia. 1994; 35(Suppl 8):S67.

17. Shank RP, Gardocki JF, Vaught JL et al. Topiramate: preclinical evaluation of structurally novel anticonvulsant. Epilepsia. 1994; 35:450-60. [PubMed 8156972]

18. Edmonds HL Jr, Jiang YD, Zhang PY et al. Anticonvulsant activity of topiramate and phenytoin in a rat model of ischemia-induced epilepsy. Life Sci. 1996; 59:PL127-31. [PubMed 8761322]

19. White HS. Clinical significance of animal seizure models and mechanism of action studies of potential antiepileptic drugs. Epilepsia. 1997; 38(Suppl 1):S9-17. [PubMed 9092952]

20. Nakamura J, Tamura S, Kanda T et al. Inhibition by topiramate of seizures in spontaneously epileptic rats and DBA/2 mice. Eur J Pharmacol. 1994; 254:83-9. [PubMed 8206119]

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