Topiragen

Topiramate is a prescription medication used to treat certain types of seizures in adults and children.  It is also used to prevent migraines in adults and in adolescents ages 12 to 17. Topiramate belongs to a group of drugs called anticonvulsants, which decrease abnormal brain activity.

This medication comes in tablet form. Swallow tablets whole. Topiramate is also available in sprinkle capsules (regular and extended release capsules).

Common side effects of  topiramate include tingling of the limbs, decrease in appetite, and nausea.  Topiramate can cause vision changes, dizziness, and drowsiness.  Do not drive or operate machinery until you know how topiramate will affect you. 

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• other medicines for epilepsy (phenytoin, carbamazepine, and valproic acid)
• birth control medicines taken by mouth (oral contraceptives)
• metformin
• lithium
• other carbonic anydrase inhibitors (zonisamide, acetazolamide, dichlorphenamide)
• CNS depressants (medicines that impair your thinking, concentration or muscle coordination). For example:
  • medicines for anxiety 
  • medicines for insomnia
  • pain medicines
  • alcohol

This is not a complete list of possible drug interactions with topiramate. Talk to your doctor or pharmacist for more information.

Topiramate can harm your unborn baby.

• If you take topiramate during pregnancy, your baby has a higher risk for birth defects called cleft lip and cleft palate. These defects can begin early in pregnancy, even before you know you are pregnant.
• Cleft lip and cleft palate may happen even in children born to women who are not taking any medicines and do not have other risk factors.
• There may be other medicines to treat your condition that have a lower chance of birth defects.
• All women of childbearing age should talk to their healthcare providers about using other possible treatments instead of topiramate. If the decision is made to use topiramate, you should use effective birth control (contraception) unless you are planning to become pregnant. You should talk to your doctor about the best kind of birth control to use while you are taking topiramate.
• Tell your healthcare provider right away if you become pregnant while taking topiramate. You and your healthcare provider should decide if you will continue to take topiramate while you are pregnant.
• Metabolic acidosis may have harmful effects on your baby. Talk to your healthcare provider if topiramate has caused metabolic acidosis during your pregnancy.
• Pregnancy Registry: If you become pregnant while taking topiramate, talk to your healthcare provider about registering with the North American Antiepileptic Drug Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. The purpose of this registry is to collect information about the safety of antiepileptic drugs during pregnancy.

If you take too much topiramate, call your local Poison Control Center or seek emergency medical attention right away.

In the U.S.

• Qudexy XR
• Topamax
• Topiragen
• Trokendi XR

Available Dosage Forms:

• Tablet
• Capsule, Extended Release
• Capsule

Therapeutic Class: Anticonvulsant

Chemical Class: Fructopyranose Sulfamate

Topiramate is used alone or together with other medicines to help treat certain types of seizures (eg, partial seizures, tonic-clonic seizures, or Lennox-Gastaut syndrome). This medicine will not cure epilepsy and will only work to control seizures for as long as you continue to take it. It is also used to help prevent migraine headaches.

This medicine is available only with your doctor's prescription.

Monotherapy Epilepsy

Topiragen™ (topiramate) Tablets are indicated as initial monotherapy in patients 10 years of age and older with partial onset or primary generalized tonic-clonic seizures.

Effectiveness was demonstrated in a controlled trial in patients with epilepsy who had no more than 2 seizures in the 3 months prior to enrollment. Safety and effectiveness in patients who were converted to monotherapy from a previous regimen of other anticonvulsant drugs have not been established in controlled trials.

Adjunctive Therapy Epilepsy

Topiragen™ (topiramate) Tablets are indicated as adjunctive therapy for adults and pediatric patients ages 2-16 years with partial onset seizures, or primary generalized tonic-clonic seizures, and in patients 2 years of age and older with seizures associated with Lennox-Gastaut syndrome.

Hyperammonemia and Encephalopathy Associated with Concomitant Valproic Acid Use

Concomitant administration of topiramate and valproic acid has been associated with hyperammonemia with or without encephalopathy in patients who have tolerated either drug alone. Clinical symptoms of hyperammonemic encephalopathy often include acute alterations in level of consciousness and/or cognitive function with lethargy or vomiting. In most cases, symptoms and signs abated with discontinuation of either drug. This adverse event is not due to a pharmacokinetic interaction.

It is not known if topiramate monotherapy is associated with hyperammonemia.

Patients with inborn errors of metabolism or reduced hepatic mitochondrial activity may be at an increased risk for hyperammonemia with or without encephalopathy. Although not studied, an interaction of topiramate and valproic acid may exacerbate existing defects or unmask deficiencies in susceptible persons.

In patients who develop unexplained lethargy, vomiting, or changes in mental status, hyperammonemic encephalopathy should be considered and an ammonia level should be measured.

Kidney Stones

A total of 32/2,086 (1.5%) of adults exposed to topiramate during its adjunctive epilepsy therapy development reported the occurrence of kidney stones, an incidence about 2-4 times greater than expected in a similar, untreated population. In the double-blind monotherapy epilepsy study, a total of 4/319 (1.3%) of adults exposed to topiramate reported the occurrence of kidney stones. As in the general population, the incidence of stone formation among topiramate treated patients was higher in men. Kidney stones have also been reported in pediatric patients.

An explanation for the association of topiramate and kidney stones may lie in the fact that topiramate is a carbonic anhydrase inhibitor. Carbonic anhydrase inhibitors, e.g., acetazolamide or dichlorphenamide, promote stone formation by reducing urinary citrate excretion and by increasing urinary pH. The concomitant use of topiramate with other carbonic anhydrase inhibitors or potentially in patients on a ketogenic diet may create a physiological environment that increases the risk of kidney stone formation, and should therefore be avoided.

Increased fluid intake increases the urinary output, lowering the concentration of substances involved in stone formation. Hydration is recommended to reduce new stone formation.

Paresthesia

Paresthesia (usually tingling of the extremities), an effect associated with the use of other carbonic anhydrase inhibitors, appears to be a common effect of topiramate. Paresthesia was more frequently reported in the monotherapy epilepsy trials versus the adjunctive therapy epilepsy trials. In the majority of instances, paresthesia did not lead to treatment discontinuation.

Adjustment of Dose in Renal Failure

The major route of elimination of unchanged topiramate and its metabolites is via the kidney. Dosage adjustment may be required in patients with reduced renal function (see DOSAGE AND ADMINISTRATION).

Decreased Hepatic FunctioN

In hepatically impaired patients, topiramate should be administered with caution as the clearance of topiramate may be decreased.

Information for Patients

Patients and their caregivers should be informed of the availability of a Medication Guide, and they should be instructed to read the Medication Guide prior to taking Topiragen™ Tablets. Patients should be instructed to take Topiragen™ Tablets only as prescribed.

Patients taking Topiragen™ Tablets should be told to seek immediate medical attention if they experience blurred vision or periorbital pain.

Patients, especially pediatric patients, treated with Topiragen™ Tablets should be monitored closely for evidence of decreased sweating and increased body temperature, especially in hot weather.

Patients, their caregivers and families should be counseled that AEDs, including Topiragen™ Tablets, may increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of 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.

Patients, particularly those with predisposing factors, should be instructed to maintain an adequate fluid intake in order to minimize the risk of renal stone formation [see PRECAUTIONS: Kidney Stones, for support regarding hydration as a preventative measure].

Patients should be warned about the potential for somnolence, dizziness, confusion, and difficulty concentrating and advised not to drive or operate machinery until they have gained sufficient experience on topiramate to gauge whether it adversely affects their mental performance and/or motor performance.

Additional food intake may be considered if the patient is losing weight while on this medication.

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 (see PRECAUTIONS: Pregnancy: Pregnancy Category C).

Laboratory Tests:

Measurement of baseline and periodic serum bicarbonate during topiramate treatment is recommended (see WARNINGS).

Drug Interactions:

In vitro studies indicate that topiramate does not inhibit enzyme activity for CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4/5 isozymes.

Potential interactions between topiramate and standard AEDs were assessed in controlled clinical pharmacokinetic studies in patients with epilepsy. The effects of these interactions on mean plasma AUCs are summarized in Table 4.

In Table 4, the second column (AED concentration) describes what happens to the concentration of the AED listed in the first column when topiramate is added.

The third column (topiramate concentration) describes how the coadministration of a drug listed in the first column modifies the concentration of topiramate in experimental settings when topiramate was given alone.

In addition to the pharmacokinetic interaction described in the above table, concomitant administration of valproic acid and topiramate has been associated with hyperammonemia with and without encephalopathy (see PRECAUTIONS, Hyperammonemia and Encephalopathy Associated with Concomitant Valproic Acid Use).

Other Drug Interactions

Digoxin:  In a single-dose study, serum digoxin AUC was decreased by 12% with concomitant topiramate administration. The clinical relevance of this observation has not been established.

CNS Depressants: Concomitant administration of topiramate and alcohol or other CNS depressant drugs has not been evaluated in clinical studies. Because of the potential of topiramate to cause CNS depression, as well as other cognitive and/or neuropsychiatric adverse events, topiramate should be used with extreme caution if used in combination with alcohol and other CNS depressants.

Oral Contraceptives:  In a pharmacokinetic interaction study in healthy volunteers with a concomitantly administered combination oral contraceptive product containing 1 mg norethindrone (NET) plus 35 mcg ethinyl estradiol (EE), topiramate given in the absence of other medications at doses of 50 to 200 mg/day was not associated with statistically significant changes in mean exposure (AUC) to either component of the oral contraceptive. In another study, exposure to EE was statistically significantly decreased at doses of 200, 400, and 800 mg/day (18%, 21%, and 30%, respectively) when given as adjunctive therapy in patients taking valproic acid. In both studies, topiramate (50 mg/day to 800 mg/day) did not significantly affect exposure to NET. Although there was a dose dependent decrease in EE exposure for doses between 200-800 mg/day, there was no significant dose dependent change in EE exposure for doses of 50-200 mg/day. The clinical significance of the changes observed is not known. 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.

Hydrochlorothiazide (HCTZ): A drug-drug interaction study conducted in healthy volunteers evaluated the steady-state pharmacokinetics of HCTZ (25 mg q24h) and topiramate (96 mg q12h) when administered alone and concomitantly. The results of this study indicate that topiramate Cmax increased by 27% and AUC increased by 29% when HCTZ was added to topiramate. The clinical significance of this change is unknown. The addition of HCTZ to topiramate therapy may require an adjustment of the topiramate dose. The steady-state pharmacokinetics of HCTZ were not significantly influenced by the concomitant administration of topiramate. Clinical laboratory results indicated decreases in serum potassium after topiramate or HCTZ administration, which were greater when HCTZ and topiramate were administered in combination.

Pioglitazone: A drug-drug interaction study conducted in healthy volunteers evaluated the steady-state pharmacokinetics of topiramate and pioglitazone when administered alone and concomitantly. A 15% decrease in the AUCτ,ss of pioglitazone with no alteration in Cmax,ss was observed. This finding was not statistically significant. In addition, a 13% and 16% decrease in Cmax,ss and AUCτ,ss respectively, of the active hydroxy-metabolite was noted as well as a 60% decrease in Cmax,ss and AUCτ,ss of the active keto-metabolite. The clinical significance of these findings is not known. When Topiragen™ (topiramate) Tablets are added to pioglitazone therapy or pioglitazone is added to Topiragen™ (topiramate) Tablets therapy, careful attention should be given to the routine monitoring of patients for adequate control of their diabetic disease state.

Lithium: Multiple dosing of topiramate 100 mg every 12 hrs decreased the AUC and Cmax of Lithium (300 mg every 8 hrs) by 20% (N=12, 6 M; 6 F).

Haloperidol: The pharmacokinetics of a single dose of haloperidol (5 mg) were not affected following multiple dosing of topiramate (100 mg every 12 hr) in 13 healthy adults (6 M, 7 F).

Amitriptyline: There was a 12% increase in AUC and Cmax for amitriptyline (25 mg per day) in 18 normal subjects (9 male; 9 female) receiving 200 mg/day of topiramate. Some subjects may experience a large increase in amitriptyline concentration in the presence of topiramate and any adjustments in amitriptyline dose should be made according to the patient's clinical response and not on the basis of plasma levels.

Sumatriptan: Multiple dosing of topiramate (100 mg every 12 hrs) in 24 healthy volunteers (14 M, 10 F) did not affect the pharmacokinetics of single dose sumatriptan either orally (100 mg) or subcutaneously (6 mg).

Risperidone: There was a 25% decrease in exposure to risperidone (2 mg single dose) in 12 healthy volunteers (6 M, 6 F) receiving 200 mg/day of topiramate. Therefore, patients receiving risperidone in combination with topiramate should be closely monitored for clinical response.

Propranolol: Multiple dosing of topiramate (200 mg/day) in 34 healthy volunteers (17 M, 17 F) did not affect the pharmacokinetics of propranolol following daily 160 mg doses. Propranolol doses of 160 mg/day in 39 volunteers (27 M, 12 F) had no effect on the exposure to topiramate at a dose of 200 mg/day of topiramate.

Dihydroergotamine: Multiple dosing of topiramate (200 mg/day) in 24 healthy volunteers (12 M, 12 F) did not affect the pharmacokinetics of a 1 mg subcutaneous dose of dihydroergotamine. Similarly, a 1 mg subcutaneous dose of dihydroergotamine did not effect the pharmacokinetics of a 200 mg/day dose of topiramate in the same study.

Others:  Concomitant use of Topiragen™ (topiramate) Tablets, a carbonic anhydrase inhibitor, with other carbonic anhydrase inhibitors, e.g., acetazolamide or dichlorphenamide, may create a physiological environment that increases the risk of renal stone formation, and should therefore be avoided.

Drug/Laboratory Tests Interactions:  There are no known interactions of topiramate with commonly used laboratory tests.

Carcinogenesis, Mutagenesis, Impairment of Fertility:

An increase in urinary bladder tumors was observed in mice given topiramate (20, 75, 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).

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.

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).

Pregnancy: Pregnancy Category C.

Topiramate has demonstrated selective developmental toxicity, including teratogenicity, in experimental animal studies. When oral doses of 20, 100, 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/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, 100, and 500 mg/kg or 0.2, 2.5, 30, 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, 60, and 180 mg/kg or 10, 35, 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, 4, 20, 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, 2.5, 30, 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.

There are no studies using topiramate in pregnant women. Topiramate should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

In post-marketing experience, cases of hypospadias have been reported in male infants exposed in utero to topiramate, with or without other anticonvulsants; however, a causal relationship with topiramate has not been established.

To provide information regarding the effects of in utero exposure to Topiragen™ Tablets physicians are advised to recommend that pregnant patients taking Topiragen™ Tablets enroll in the NAAED Pregnancy Registry. This can be done by calling the toll free number, 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.

Labor and Delivery:

In studies of rats where dams were allowed to deliver pups naturally, no drug-related effects on gestation length or parturition were observed at dosage levels up to 200 mg/kg/day.

The effect of topiramate on labor and delivery in humans is unknown.

Nursing Mothers:

Topiramate is excreted in the milk of lactating rats. The excretion of topiramate in human milk has not been evaluated in controlled studies. Limited observations in patients suggest an extensive secretion of topiramate into breast milk. Since many drugs are excreted in human milk, and because the potential for serious adverse reactions in nursing infants to topiramate is unknown, the potential benefit to the mother should be weighed against the potential risk to the infant when considering recommendations regarding nursing.

Pediatric Use:

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. Safety and effectiveness in patients below the age of 10 years have not been established for the monotherapy treatment of epilepsy. Topiramate is associated with metabolic acidosis. Chronic untreated metabolic acidosis in pediatric patients may cause osteomalacia/rickets and may reduce growth rates. A reduction in growth rate may eventually decrease the maximal height achieved. The effect of topiramate on growth and bone-related sequelae has not been systematically investigated (see WARNINGS).

Geriatric Use:

In clinical trials, 3% of patients were over 60. No age related difference in effectiveness or adverse effects were evident. However, clinical studies of topiramate did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. Dosage adjustment may be necessary for elderly with impaired renal function (creatinine clearance rate ≤ 70 mL/min/1.73 m2) due to reduced clearance of topiramate (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).

Race and Gender Effects:

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

Common side effects of Topiragen include: anxiety, ataxia, confusion, diarrhea, diplopia, dizziness, drowsiness, dysphasia, fatigue, lack of concentration, memory impairment, nausea, nervousness, paresthesia, psychomotor disturbance, speech disturbance, depression, visual disturbance, weight loss, dysgeusia, mood changes, and anorexia. Other side effects include: arthralgia, and asthenia. See below for a comprehensive list of adverse effects.

Applies to topiramate: oral capsule, oral capsule extended release, oral tablet

Along with its needed effects, topiramate (the active ingredient contained in Topiragen) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking topiramate:

• Any vision problems, especially blurred vision, double vision, eye pain, or rapidly decreasing vision
• burning, prickling, or tingling sensations
• clumsiness or unsteadiness
• confusion
• continuous, uncontrolled back-and-forth or rolling eye movements
• dizziness
• drowsiness
• eye redness
• generalized slowing of mental and physical activity
• increased eye pressure
• memory problems
• menstrual changes
• menstrual pain
• nervousness
• speech or language problems
• trouble in concentrating or paying attention
• unusual tiredness or weakness

• Abdominal or stomach pain
• fever, chills, or sore throat
• lessening of sensations or perception
• loss of appetite
• mood or mental changes, including aggression, agitation, apathy, irritability, and mental depression
• red, irritated, or bleeding gums
• weight loss

• Blood in the urine
• decrease in sexual performance or desire
• difficult or painful urination
• frequent urination
• hearing loss
• loss of bladder control
• lower back or side pain
• nosebleeds
• pale skin
• red or irritated eyes
• ringing or buzzing in the ears
• skin rash or itching
• swelling
• trouble breathing

• Blistering, peeling, or loosening of the skin
• blisters in the mouth
• blisters on the trunk, scalp, or other areas
• bloating
• clay-colored stools
• constipation
• cough
• diarrhea
• increased rate of breathing
• joint or muscle pain
• pain or tenderness in upper abdomen or stomach
• red skin lesions, often with a purple center
• sores, ulcers, or white spots in the mouth or on the lips
• yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking topiramate:

• Decreased awareness or responsiveness
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• severe sleepiness
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

Some side effects of topiramate may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Breast pain in women
• tremors

• Back pain
• chest pain
• constipation
• heartburn
• hot flushes
• increased sweating
• leg pain