Topiramate (Topamax)

Primer

Topiramate (Trade name: Topamax) is an anticonvulsant used to treat epilepsy and prevent migraines. It is also used in the treatment of alcohol use disorder.

Pharmacokinetics

See also article: Introduction to Pharmacology

Pharmacokinetics of Topiramate

Absorption
Distribution
Metabolism
Elimination
Half-life

See also article: Cytochrome (CYP) P450 Metabolism

Topiramate: Cytochrome P450 Metabolism

Substrate of (Metabolized by)
Induces
Inhibits

Pharmacodynamics

Mechanism of Action

Blocks Na+ channels
Increases GABA activity

Toxicity

Indications

Seizure disorders
Stimulant use disorder (cocaine and stimulant)
Possibly for aggression, alcoholism, anger, impulsivity (off-label)

Dosing

Dosing for Topiramate

Starting
Titration
Maximum
Taper

Formulations

Topiramate comes in

Monitoring

Contraindications

Absolute

Relative

Drug-Drug Interactions

Side Effects

Sedation, cognitive impairment can be significant (pejoratively called “Dopamax”)
Weight loss

Adverse Events

Topiramate increases the risk for nephrolithiasis (kidney stones) due to hypocitraturia and high urine pH^[1]^[2]
- However, it is not an absolute contraindication in patients with kidney stones^[3]
Topiramate has been associated with glaucoma.^[4]

Clinical Pearls

Special Populations

Geriatric

See main article: Geriatric Pharmacology

Pediatric

See main article: Pediatric Pharmacology

Obstetric and Fetal

See main article: Obstetric and Fetal Pharmacology

Increases the risk for offspring to develop cleft palate in pregnancy

Medically Ill

See main article: Psychotropic Dosing in the Medically Ill

Resources

¹⁾ Maalouf, N. M., Langston, J. P., Van Ness, P. C., Moe, O. W., & Sakhaee, K. (2011). Nephrolithiasis in topiramate users. Urological research, 39(4), 303-307.

²⁾ Lamb, E. J., Stevens, P. E., & Nashef, L. (2004). Topiramate increases biochemical risk of nephrolithiasis. Annals of clinical biochemistry, 41(2), 166-169.

³⁾ Jion, Y. I., Raff, A., Grosberg, B. M., & Evans, R. W. (2015). The risk and management of kidney stones from the use of topiramate and zonisamide in migraine and idiopathic intracranial hypertension. Headache: The Journal of Head and Face Pain, 55(1), 161-166.

⁴⁾ Craig, J. E., Ong, T. J., Louis, D. L., & Wells, J. M. (2004). Mechanism of topiramate-induced acute-onset myopia and angle closure glaucoma. American journal of ophthalmology, 137(1), 193-195.

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