What are the indications for Topamax (topiramate)?

Topamax (Topiramate) Indications

Topamax is FDA-approved for epilepsy (as monotherapy or adjunctive therapy) and migraine prevention, and is also approved in combination with phentermine for chronic weight management in adults with obesity. 1

FDA-Approved Indications

Epilepsy Treatment

Monotherapy:

• Initial monotherapy for patients ≥10 years old with partial-onset seizures or primary generalized tonic-clonic seizures 1
• Target dose of 100 mg/day for adults with new-onset seizures 2

Adjunctive Therapy:

• Adults and children ages 2-16 years with partial-onset seizures 1
• Adults and children ages 2-16 years with primary generalized tonic-clonic seizures 1
• Patients ≥2 years old with seizures associated with Lennox-Gastaut syndrome 1
• Higher dosages (up to 400 mg/day) may be needed for refractory seizures or when combined with enzyme-inducing drugs 2

Migraine Prevention

• Approved for migraine prophylaxis in adults in the US and multiple other countries 3
• Target dose of 100 mg/day is recommended as the initial goal, with no additional efficacy demonstrated at 200 mg/day 3
• Start at 25 mg daily and increase by 25 mg weekly to reach 100 mg/day (50 mg twice daily or 100 mg at night) 4
• Consider topiramate preferentially in patients with both migraines and obesity, as it addresses both conditions simultaneously 5

Obesity Management (Combination Therapy Only)

Phentermine-topiramate extended-release is approved for chronic weight management in adults with:

• BMI ≥30 kg/m² OR 6
• BMI ≥27 kg/m² with at least one weight-related complication (hypertension, type 2 diabetes, dyslipidemia) 6

Dosing for obesity:

• Start at 3.75 mg phentermine/23 mg topiramate daily for 14 days 6
• Increase to maintenance dose of 7.5 mg/46 mg daily 6
• Can escalate to 11.25 mg/69 mg for 14 days, then maximum dose of 15 mg/92 mg daily if tolerated and additional weight loss desired 6
• Discontinue if <3% weight loss after 12 weeks at 7.5/46 mg, or <5% weight loss after 12 weeks at maximum dose 6

Off-Label Uses Supported by Evidence

While not FDA-approved, topiramate has demonstrated efficacy in:

• Substance dependence 7
• Bipolar disorder 7
• Neuropathic pain 7
• PTSD-related nightmares (start at 12.5-25 mg daily, increase by 25-50 mg every 3-4 days) 4
• Cyclic vomiting syndrome prophylaxis (start at 25 mg nightly, titrate by 25 mg every 2 weeks to 100-150 mg daily) 4

Critical Prescribing Considerations

Absolute Contraindications:

• Pregnancy or women of childbearing potential without reliable contraception (causes neural tube defects and orofacial clefts) 6, 8
• Uncontrolled hypertension (for phentermine-topiramate combination) 8
• History of cardiovascular disease (for phentermine-topiramate combination) 6, 8
• Concomitant use with MAOIs or within 14 days of MAOI discontinuation 6, 8

Mandatory Patient Counseling:

• Teratogenic risk and need for effective contraception in women of childbearing potential 6, 4
• Topiramate reduces efficacy of hormonal contraceptives, requiring additional contraceptive methods 4, 8
• Monthly pregnancy testing should be considered 6
• Risk of cognitive slowing, paresthesias, kidney stones, and metabolic acidosis 6, 4
• Never discontinue abruptly—taper by taking one capsule every other day for at least 1 week to prevent seizure precipitation 6, 5

Common Pitfalls:

• Starting at too high a dose or titrating too rapidly increases cognitive side effects and discontinuation rates 2, 9
• Failing to monitor serum bicarbonate for metabolic acidosis with long-term use 6, 4
• Not counseling about contraceptive interactions before prescribing to women of childbearing age 4, 8
• Using phentermine-topiramate in patients with cardiovascular disease or untreated hyperthyroidism 6