Topiramate

Anticonvulsant·Neurology - Anticonvulsants

Migraine prophylaxis, focal and generalized epilepsy

Authority requiredPBSMIGRAINE/SEIZURETopamax, Tamate25 mg tablet+2

Max Dose

400 mg/day

Half-life

21 h

Cognitive

DOPAMAX

Weight Loss

COMMON

Rapid Summary

Overview

Broad-spectrum anticonvulsant and migraine prophylactic. Causes significant weight loss and appetite suppression, but is notorious for inducing 'brain fog' and word-finding difficulties.

Maximum Dose

Max 400 mg/day (For epilepsy). Max 100 mg/day (For migraine).

Clinical Focus

Can precipitate acute angle-closure glaucoma and kidney stones.

Bottom Line

Topiramate is a broad-spectrum anticonvulsant also used for migraine prophylaxis and weight loss, but causes significant cognitive dulling, word-finding difficulty, and nephrolithiasis.

Formulation & Access

Brand Names

Topamax, Tamate

Oral Routes

Tablets (25 mg, 50 mg, 100 mg, 200 mg). Sprinkle capsules.

Prescribing & PBS

Authority Required (PBS).

Indications & Use

Primary

PBSTGA

Migraine prophylaxis, focal and generalized epilepsy.

Off-Label

OFF

Weight loss (combined with phentermine), binge eating disorder.

Clinical Place

Highly favored in young patients with migraines who wish to avoid weight-gaining drugs (like Valproate or Amitriptyline).

Quick reference

Class & Role

Anticonvulsant — Broad-spectrum anticonvulsant and migraine prophylactic.

Route / Formulation

Tablets (25 mg, 50 mg, 100 mg, 200 mg). Sprinkle capsules. (Topamax, Tamate)

Usual Dose & Max

Start PO 25 mg NOCTE. Titrate up by 25 mg weekly to target 50 mg BD (100 mg/day). Max 400 mg/day (For epilepsy).

Key Indication Doses

Migraine Prophylaxis: Start PO 25 mg NOCTE. Titrate up by 25 mg weekly to target 50 mg BD (100 mg/day). Epilepsy: PO 25-50 mg OD, titrate up to 100-200 mg BD. Renal Impairment: Halve the dose if eGFR < 70.

Best Uses

Topiramate is a broad-spectrum anticonvulsant also used for migraine prophylaxis and weight loss, but causes significant cognitive dulling, word-finding difficulty, and nephrolithiasis.

Avoid / Cautions

History of kidney stones, untreated glaucoma. Pregnancy Category D. High risk of cleft lip/palate. Must use strict contraception.

Key Risks

Neurological: Cognitive blunting, word-finding difficulty, memory impairment, paresthesia (tingling in fingers/toes). Metabolic: Weight loss, anorexia. MODERATE — Non-anion gap metabolic acidosis (due to renal bicarbonate wasting from carbonic anhydrase inhibition). Ocular: Acute secondary angle-closure glaucoma (sudden severe eye pain/blurriness). Renal: Nephrolithiasis (Calcium phosphate kidney stones).

Key Interactions

Doses > 200mg/day induce CYP3A4, accelerating the clearance of oral contraceptives (OCPs), rendering them ineffective and leading to unplanned pregnancies.

Monitoring

Monitor U&E (specifically serum bicarbonate) for metabolic acidosis. Counsel heavily on maintaining high fluid intake to prevent kidney stones. Ask about eye pain/vision changes.

Clinical Pearl

Topiramate is infamous for causing psychomotor slowing and making patients feel 'stupid'. They will frequently forget mid-sentence what they were saying. Start the dose very low and escalate slowly to mitigate this.

Access

Authority requiredTopamax, Tamate25 mg tablet

Brand: Topamax, Tamate
PBS status: Authority required
Formulation: Tablets (25 mg, 50 mg, 100 mg, 200 mg)

Topiramate

Anticonvulsant·Neurology - Anticonvulsants

Migraine prophylaxis, focal and generalized epilepsy

Authority requiredPBSMIGRAINE/SEIZURETopamax, Tamate25 mg tablet+2

Max Dose

400 mg/day

Half-life

21 h

Cognitive

DOPAMAX

Weight Loss

COMMON

Rapid Summary

Overview

Broad-spectrum anticonvulsant and migraine prophylactic. Causes significant weight loss and appetite suppression, but is notorious for inducing 'brain fog' and word-finding difficulties.

Maximum Dose

Max 400 mg/day (For epilepsy). Max 100 mg/day (For migraine).

Clinical Focus

Can precipitate acute angle-closure glaucoma and kidney stones.

Bottom Line

Topiramate is a broad-spectrum anticonvulsant also used for migraine prophylaxis and weight loss, but causes significant cognitive dulling, word-finding difficulty, and nephrolithiasis.

Formulation & Access

Brand Names

Topamax, Tamate

Oral Routes

Tablets (25 mg, 50 mg, 100 mg, 200 mg). Sprinkle capsules.

Prescribing & PBS

Authority Required (PBS).

Indications & Use

Primary

PBSTGA

Migraine prophylaxis, focal and generalized epilepsy.

Off-Label

OFF

Weight loss (combined with phentermine), binge eating disorder.

Clinical Place

Highly favored in young patients with migraines who wish to avoid weight-gaining drugs (like Valproate or Amitriptyline).

Quick reference

Class & Role

Anticonvulsant — Broad-spectrum anticonvulsant and migraine prophylactic.

Route / Formulation

Tablets (25 mg, 50 mg, 100 mg, 200 mg). Sprinkle capsules. (Topamax, Tamate)

Usual Dose & Max

Start PO 25 mg NOCTE. Titrate up by 25 mg weekly to target 50 mg BD (100 mg/day). Max 400 mg/day (For epilepsy).

Key Indication Doses

Best Uses

Topiramate is a broad-spectrum anticonvulsant also used for migraine prophylaxis and weight loss, but causes significant cognitive dulling, word-finding difficulty, and nephrolithiasis.

Avoid / Cautions

History of kidney stones, untreated glaucoma. Pregnancy Category D. High risk of cleft lip/palate. Must use strict contraception.

Key Risks

Key Interactions

Doses > 200mg/day induce CYP3A4, accelerating the clearance of oral contraceptives (OCPs), rendering them ineffective and leading to unplanned pregnancies.

Monitoring

Monitor U&E (specifically serum bicarbonate) for metabolic acidosis. Counsel heavily on maintaining high fluid intake to prevent kidney stones. Ask about eye pain/vision changes.

Clinical Pearl

Access

Authority requiredTopamax, Tamate25 mg tablet

Brand: Topamax, Tamate
PBS status: Authority required
Formulation: Tablets (25 mg, 50 mg, 100 mg, 200 mg)