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Topiramate information from DrugsUpdate  

See Available Brands of Topiramate in India

P - Caution when used during pregnancy
L - Contraindicated in lactation

Topiramate is a seizure medication, also called an anticonvulsant. Topiramate is used alone or in combination with other medications to prevent seizures in adults and children who are at least 2 years old. Topiramate is also used to prevent migraine headaches.

Pharmacodynamics

Topiramate has anticonvulsant activity in rat and mouse maximal electroshock seizure (MES) tests. Topiramate is only weakly effective in blocking clonic seizures induced by the GABAA receptor antagonist, pentylenetetrazole. Topiramate is also effective in rodent models of epilepsy, which include tonic and absence-like seizures in the spontaneous epileptic rat (SER) and tonic and clonic seizures induced in rats by kindling of the amygdala or by global ischemia.

Pharmacokinetics

Topiramate is a sulfamate-substituted monosaccharide with precise mechanism of action unknown. It may be due to various mechanisms e.g. blocking of voltage-dependent sodium channels; augmenting the activity of γ-aminobutyric acid (GABA) at GABA-A receptor; antagonising AMPA/kainate glutamate receptors; inhibiting carbonic anhydrase.

Absorption

Readily absorbed from the GI tract (oral); peak plasma concentrations after 2 hours. Bioavailability unaffected by food.

Distribution
Protein-binding: 9-17%. Volume of distribution in man is double that in woman. Crosses the placenta, distributed into breast milk.

Metabolism
Not extensively metabolised.

Excretion

Excreted by urine (as unchanged drug and metabolites); elimination half-life: 21 hours. Children has a higher clearance and shorter elimination half-life than adults.

Topiramate Indications / Topiramate Uses

Information Not Available

Topiramate Adverse Reactions / Topiramate Side Effects

Confusion, dizziness, drowsiness, generalised slowing of mental and physical activity, difficulty with concentrations, ataxia, paresthesia, anorexia, weight loss, abnormal vision, metabolic acidosis, mood or mental changes, behavioural disturbances, depression, fatigue, agitation, nervousness, anxiety, oligohidrosis, hyperthermia and hyperammonaemic encephalopathy.

Precautions

Information Not Available

Special Precautions

Renal or hepatic impairment, pregnancy. May impair ability to drive or operate machinery. Maintain adequate hydration to reduce the risk of renal calculi especially in predisposed patients. Measure serum bicarbonate at baseline and periodically during treatment. Avoid abrupt withdrawal; decrease dose by 100 mg daily at wkly intervals. Seek immediate medical attention if blurred vision or eye pain. Monitor closely for decreased sweating and increased body temperature, especially in hot weather. Ensure proper hydration before and during activities or exposure to warm temperatures.

Other Drug Interactions

Coadmin with antiepileptic drugs e.g. phenytoin, carbamazepine, phenobarbital decreases plasma concentration of topiramate. Possible increase in phenytoin levels. Increased risk of renal stone formation with carbonic anhydrase inhibitors e.g. acetazolamide. Increased risk of CNS depression with CNS depressants and alcohol. Increased risk of hyperammonaemia and encephalopathy with valproic acid. Increased risk of contraceptive failure in women taking combined oral contraceptives.

Other Interactions

Information Not Available

Dosage

Oral
Adjunct for seizures associated with the Lennox-gastaut syndrome
Adult: Initially, 25 mg at night for 1 week, thereafter increase in steps of 25–50 mg at intervals of 1–2 weeks until effective dose is achieved. Doses >25 mg/day should be taken in 2 divided doses. Usual dose: 200–400 mg daily. Max: 800 mg daily.
Child: 2-16 years: Initially, 25 mg nightly for the 1st week increased at intervals of 1-2 weeks by increments of 1-3 mg/kg daily according to response. Daily doses of >25 mg should be taken in 2 divided doses. Usual dose: 5-9 mg/kg daily. Max: 30 mg/kg/day.

Renal impairment: Moderate to severe: Doses should be halved. Haemodialysis: Supplemental dose equal to about ½ of the daily dose should be given in divided doses (at the start and finish of haemodialysis).
Hepatic impairment: Dosage adjustment may be needed.

Oral
Epilepsy
Adult: Monotherapy: Initially, 25 mg at night for 1 week, thereafter increase in steps of 25–50 mg at intervals of 1–2 weeks. Doses >25 mg/day should be taken in 2 divided doses. Usual dose: 100-400 mg daily. Max: 400 mg daily. Adjunctive treatment: Initially, 25 mg at night for 1 week, thereafter increase in steps of 25–50 mg at intervals of 1–2 weeks until effective dose is achieved. Doses >25 mg/day should be taken in 2 divided doses. Usual dose: 200–400 mg daily. Max: 800 mg daily.
Child: 10-16 years: Initially, 0.5-1 mg/kg at night for the 1st week, increased at intervals of 1-2 weeks by increments of 0.5 to 1 mg/kg daily. Usual dose: 3-6 mg/kg daily. Daily doses >25 mg should be taken in 2 divided doses. Max: 16 mg/kg/day.

Renal impairment: Moderate to severe: Doses should be halved. Haemodialysis: Supplemental dose equal to about ½ of the daily dose should be given in divided doses (at the start and finish of haemodialysis).
Hepatic impairment: Dosage adjustment may be needed.

Oral
Prophylaxis of migraine
Adult: >16 years: Initially 25 mg daily at night for 1 week, increased in steps of 25-mg at weekly intervals. Usual dose: 50-100 mg daily in 2 divided doses. Daily doses >25 mg should be taken in 2 divided doses.

Renal impairment: Moderate to severe: Doses should be halved. Haemodialysis: supplemental dose equal to about ½ of the daily dose should be given in divided doses (at the start and finish of haemodialysis).
Hepatic impairment: Dosage adjustment may be needed.

Food(before/after)

May be taken with or without food

List of Contraindications

Topiramate and Pregnancy

Caution when used during pregnancy

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Topiramate and Lactation

Contraindicated in lactation

Topiramate and Children

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.

Topiramate and Geriatic

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

Topiramate and Other Contraindications

Lactation

Storage

Oral
Store at 15-30°C.

Lab interference

Oral
Store at 15-30°C.

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