From the Guidelines
Topiramate is primarily used to treat epilepsy, prevent migraine headaches, and as part of a combination medication for weight loss in adults with obesity. The medication works by blocking sodium channels, enhancing GABA activity, and inhibiting glutamate receptors in the brain, which helps reduce abnormal electrical activity 1.
Key Uses and Dosages
- For epilepsy and migraine prevention, typical dosages range from 25 mg to 400 mg daily, divided into two doses 2, 3.
- As part of the phentermine-topiramate ER combination for weight loss, the recommended starter dose is 3.75 mg/23 mg taken once daily for 14 days, followed by a maintenance dose of 7.5 mg/46 mg daily, with the option to escalate to 15 mg/92 mg daily for superior efficacy, as long as the balance of benefit and risk is favorable for the individual patient 1.
Important Considerations
- Common side effects include tingling sensations, taste changes, weight loss, cognitive slowing, and kidney stones 1, 2, 3.
- Patients should stay well-hydrated while taking this medication to reduce kidney stone risk.
- Topiramate requires gradual dose adjustment both when starting and stopping to minimize side effects and prevent seizure recurrence.
- It should be used cautiously in pregnancy as it carries a risk of birth defects, particularly cleft lip and palate.
- The medication is also sometimes prescribed off-label for conditions like bipolar disorder, eating disorders, and alcohol dependence.
Special Precautions
- Phentermine-topiramate ER should be avoided in patients with a history of cardiovascular disease or uncontrolled hypertension due to concerns about cardiotoxicity and the potential for adverse cardiovascular outcomes 1.
- Female patients with child-bearing potential should be counseled on the risks of teratogenicity and consistent use of reliable contraception while using phentermine-topiramate ER, with consideration for monthly pregnancy tests 1.
From the FDA Drug Label
WHAT IS TOPIRAMATE TOPIRAMATE is a prescription medicine used: alone to treat seizures in patients 10 years and older with other medicines to treat seizures in adults and children over age 2
The use of Topiramate (Topamax) is as a prescription medicine to treat seizures:
- Alone in patients 10 years and older
- With other medicines in adults and children over age 2 4
From the Research
Uses of Topiramate
- Topiramate is used as an antiepileptic drug (AED) to treat various types of seizures, including partial-onset seizures, generalized tonic-clonic seizures, and seizures associated with Lennox-Gastaut syndrome 5, 6.
- It is also used for migraine prophylaxis, reducing migraine frequency and acute medication use, and improving quality of life 7, 8.
- Topiramate, in combination with phentermine, is FDA-approved for weight loss in patients with a body mass index (BMI) > 30 8.
Mechanism of Action
- Topiramate works through multiple pathways, including blocking sodium and calcium voltage-gated channels, inhibiting glutamate receptors, enhancing gamma-aminobutyric acid (GABA) receptors, and inhibiting carbonic anhydrase 5, 8.
Dosage and Administration
- The current target dosing for topiramate monotherapy is 400 mg/day for epilepsy treatment and 100 mg/day for migraine prophylaxis 8.
- Topiramate can be administered as adjunctive therapy or monotherapy, and its dosage should be individualized based on patient response and tolerance 5, 6.
Side Effects
- Common side effects of topiramate include paresthesia, confusion, fatigue, dizziness, and change in taste 8.
- More uncommon and serious adverse effects can include acute glaucoma, metabolic acidosis, nephrolithiasis, hepatotoxicity, and teratogenicity 8.
- Ophthalmic side effects, such as choroidal effusion syndrome, angle-closure glaucoma, and myopic shift, can also occur 9.