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.
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
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)
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.
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