Drug information of Topiramate

Topiramate

Drug group: Anticonvulsants

Topiramate is a seizure medicine, also called an anticonvulsant. Topiramate is used to treat seizures in adults and children who are at least 2 years old. Trokendi XR is for use in adults and children who are at least 6 years old.

Mechanism of effect

The precise mechanisms by which Topiramate exerts its anticonvulsant and other effects are unknown; however, preclinical studies have revealed four properties that may contribute to Topiramate's efficacy for epilepsy. Electrophysiological and biochemical evidence suggests that Topiramate, at pharmacologically relevant concentrations, blocks voltage-dependent sodium channels, augments the activity of the neurotransmitter gamma-aminobutyrate at some subtypes of the GABA-A receptor, antagonizes the AMPA/kainate subtype of the glutamate receptor, and inhibits the carbonic anhydrase enzyme, particularly isozymes II and IV.

Pharmacodynamic

Topiramate is an anticonvulsant indicated in the treatment of epilepsy and migraine. Topiramate enhances GABA-activated chloride channels

Pharmacokinetics

Absorption of Topiramate is rapid, with peak plasma concentrations occurring at approximately 2 hours. Topiramate is not extensively metabolized and is primarily eliminated unchanged in the urine the protein binding of Topiramate from 23% to 13% Half life:19 to 23 hours.

Dosage

Usual Adult Dose for Seizures IMMEDIATE RELEASE: MONOTHERAPY (For monotherapy for adults with partial onset seizures or primary generalized tonic-clonic seizures): Recommended dose: 400 mg orally per day in 2 divided doses of 200 mg each The dose should be achieved by titration: Week 1: 25 mg orally in the morning and 25 mg orally in the evening Week 2: 50 mg orally in the morning and 50 mg orally in the evening Week 3: 75 mg orally in the morning and 75 mg orally in the evening Week 4: 100 mg orally in the morning and 100 mg orally in the evening Week 5: 150 mg orally in the morning and 150 mg orally in the evening Week 6: 200 mg orally in the morning and 200 mg orally in the evening Usual Pediatric Dose for Seizures IMMEDIATE RELEASE: MONOTHERAPY (For patients 2 to less than 10 years with partial onset or primary generalized tonic-clonic seizures): -The dose in children 2 to less than 10 years is based on weight: Titration schedule: -Week 1: 25 mg orally per day in the evening -Week 2 (if week 1 dose is tolerated): 25 mg orally 2 times a day -Thereafter: Dosage can be increased by 25 to 50 mg orally per day each week as tolerated. -Titration to the minimum maintenance dose should be attempted over 5 to 7 weeks of the total titration period. -Based upon tolerability and seizure control, titration to a higher dose (up to the maximum maintenance dose) can be attempted with 25 to 50 mg per day in weekly increments. -The total daily dose should not exceed the maximum maintenance dose for each range of body weight: Monotherapy total daily maintenance dosing for patients 2 to less than 10 years: Up to 11 kg: Minimum dose: 150 mg per day; Maximum dose: 250 mg per day 12 to 22 kg: Minimum dose: 200 mg per day; Maximum dose: 300 mg per day 23 to 31 kg: Minimum dose: 200 mg per day; Maximum dose: 350 mg per day 32 to 38 kg: Minimum dose: 250 mg; Maximum dose: 350 mg Greater than 38 kg: Minimum dose: 250 mg per day; Maximum dose: 400 mg per day

Alerts

1-A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported in patients receiving Topiramate 2-Visual field defects (independent of elevated intraocular pressure) have been reported in clinical trials and in postmarketing experience in patients receiving Topiramate. 3-Hyperchloremic, non-anion gap, metabolic acidosis (i.e., decreased serum bicarbonate below the normal reference range in the absence of chronic respiratory alkalosis) is associated with Topiramate treatment. 4-Antiepileptic drugs (AEDs), including Topiramate, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication

Points of recommendation

1-Dosage adjustment may be required in patients with reduced renal function 2-Topiramate should be used with extreme caution if used in combination with alcohol and other CNS depressants. 3-he possibility of decreased contraceptive efficacy and increased breakthrough bleeding should be considered in patients taking combination oral contraceptive products with Topiramate.

Pregnancy level

D


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