Topiramate


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Epilepsy Initial: 25 mg at night for 1 wk, increased in increments of 25 or 50 mg at 1-2 wk interval. Doses >25 mg should be taken in 2 divided doses. Max: 500 mg/day. Adjunct for seizures associated w/ the Lennox-gastaut syndrome; Adjunct in epilepsy Initial: 25-50 mg at night for 1 wk, increased in increments of 25 or 50 mg at 1-2 wk interval. Doses >25 mg should be taken in 2 divided doses. Prophylaxis of migraine Initial: 25 mg at night for 1 wk, increased in increments of 25 mg at wkly interval. Usual dose: 50-100 mg/day in 2 divided doses. Max: 200 mg/day.
Dosage Details
Oral
Epilepsy
Adult: Initially, 25 mg at night for 1 wk, increased in increments of 25 or 50 mg at 1-2 wk interval until effective dose is reached. Doses >25 mg should be taken in 2 divided doses. Usual dose: 100 mg daily. Max: 500 mg daily.
Child: ≥6 yr Initially, 0.5-1 mg/kg at night for 1 wk, increased in increments of 0.5-1 mg/kg at 1-2 wk interval. Initial target dose: 100 mg (approx 2 mg/kg) daily in 2 divided doses.

Oral
Prophylaxis of migraine
Adult: Initially, 25 mg at night for 1 wk, increased in increments of 25 mg at wkly interval. Usual dose: 50-100 mg daily in 2 divided doses. Max: 200 mg daily.

Oral
Adjunct for seizures associated with the Lennox-gastaut syndrome, Adjunct in epilepsy
Adult: Initially, 25-50 mg at night for 1 wk, increased in increments of 25 or 50 mg at 1-2 wk interval until effective dose is reached. Doses >25 mg should be taken in 2 divided doses. Usual dose: 200-400 mg daily.
Child: ≥2 yr Initially, 25 mg at night for 1 wk, increased in increments of 1-3 mg/kg at 1-2 wk interval until effective dose is reached. Doses >25 mg should be taken in 2 divided doses. Usual dose: Approx 5-9 mg/kg daily.
Renal Impairment
Patient undergoing haemodialysis: Supplemental dose equal to approx 50% of the daily dose, given in divided doses (at the start and upon completion of haemodialysis).

CrCl (mL/min) Dosage
≤70  Reduce usual dose by 50% and titrate more slowly.
Administration
May be taken with or without food.
Special Precautions
Patient w/ predisposition to nephrolithiasis, conditions or medications that may increase risk of metabolic acidosis. Renal and hepatic impairment. Childn. Pregnancy and lactation.
Adverse Reactions
Confusion, ataxia, impaired concentration and speech, fatigue, depression, dizziness, paraesthesia or hypoaesthesia, drowsiness, memory or cognition difficulty, anxiety, agitation, nervousness, emotional lability, mood disorders, anorexia, abdominal pain, asthenia, diplopia, leucopenia, nausea, diarrhoea, nystagmus, insomnia, psychomotor retardation, nasopharyngitis, altered taste, visual disturbances, wt loss, increased risk of renal calculi, reduced sweating w/ hyperthermia. Rarely, acute myopia w/ secondary angle-closure glaucoma.
Patient Counseling Information
This drug may cause visual disturbances, drowsiness, and dizziness, if affected do not drive or operate machinery. Avoid abrupt withdrawal.
MonitoringParameters
Monitor electrolytes (e.g. serum bicarbonate) at baseline and periodically during treatment, serum creatinine, symptoms of acute acidosis and complications of long-term acidosis, hydration status, seizure frequency, and suicidality.
Overdosage
Symptoms: Drowsiness, speech disturbances, convulsions, blurred vision, diplopia, impaired mental status, lethargy, abnormal coordination, hypotension, abdominal pain, stupor, agitation, dizziness, depression. Management: Supportive treatment. Keep the patient hydrated. Employ gastric lavage, or activated charcoal, or induce emesis, if ingestion is recent.
Drug Interactions
Decreased serum level w/ other antiepileptics (e.g. carbamazepine, phenytoin). May increase effect of CNS depressants. May reduce efficacy and increase risk of breakthrough bleeding of OCs. May increase AR (e.g. metabolic acidosis) of metformin and other carbonic anhydrase inhibitors (e.g. acetazolamide). May increase serum level of lithium.
Food Interaction
May increase CNS depressant effect w/ alcohol.
Action
Description: Topiramate is a sulfamate-substituted monosaccharide w/ unknown precise mechanism of action. It may be due to blockade of voltage-dependent Na channels; augmentation of the activity of γ-aminobutyric acid (GABA) at GABAA receptors; antagonism of AMPA/kainate glutamate receptors; and inhibition of carbonic anhydrase.
Pharmacokinetics:
Absorption: Rapidly and well absorbed from the GI tract. Bioavailability: Approx 80%. Time to peak plasma concentration: Approx 2 hr.
Distribution: Crosses the placenta and enters breast milk. Plasma protein binding: Approx 15-41%.
Metabolism: Metabolised minimally in the liver via hydrolysis, hydroxylation, and glucuronidation.
Excretion: Via urine (approx 70% as unchanged drug). Elimination half-life: Approx 21 hr.
Chemical Structure

Chemical Structure Image
Topiramate

Source: National Center for Biotechnology Information. PubChem Database. Topiramate, CID=5284627, https://pubchem.ncbi.nlm.nih.gov/compound/Topiramate (accessed on Jan. 23, 2020)

Storage
Store below 25°C. Protect from moisture.
MIMS Class
ATC Classification
N03AX11 - topiramate ; Belongs to the class of other antiepileptics.
References
Anon. Topiramate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/02/2016.

Buckingham R (ed). Topiramate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/02/2016.

Joint Formulary Committee. Topiramate. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/02/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Topiramate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 04/02/2016.

Topiramate Capsule, Coated Pellets (Cardila Healthcare Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 04/02/2016.

Disclaimer: This information is independently developed by MIMS based on Topiramate from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Sign up for free
Already a member? Sign in