Topiramate
TopamaxPubChem CID 5284627 · 3D model
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Hits nerve signaling from four different angles at once — blocking a sodium switch, boosting a calming brain chemical, blocking an excitatory one, and inhibiting an enzyme tied to some of its odder side effects.
How it works
Doctors don't fully know why topiramate works, but lab research points to four separate effects happening at once, not just one. Like phenytoin, also on this site, it jams a sodium channel nerve cells use to fire signals — but unlike phenytoin, that's only one of its four tricks. It also boosts a calming brain chemical called GABA, working at a different spot than benzodiazepine sedatives like alprazolam, also on this site. On top of that, it blocks a completely different excitatory signal (glutamate acting through AMPA/kainate receptors), something most other seizure drugs, including gabapentin, also on this site, don't do at all. And finally, topiramate blocks an enzyme called carbonic anhydrase, believed to be behind some of its more unusual side effects, like kidney stones and mild blood acidity, and possibly its tendency to cause weight loss — which is why it's paired with the appetite suppressant phentermine, also on this site, in the weight-loss drug Qsymia.
What it’s used for
Used on its own or alongside other medications to control several seizure types in patients 2 and older, and to prevent migraines in patients 12 and older. The same ingredient, combined with the appetite suppressant phentermine in a separate prescription product called Qsymia, is FDA-approved for long-term weight management, but that's a different drug product with its own approval.
- Mechanism
- Multi-mechanism anticonvulsant: sodium channel blocker, GABA-A potentiator, AMPA/kainate glutamate receptor antagonist, and carbonic anhydrase inhibitor
- Drug class
- Small molecule
- Therapeutic area
- CNS / Neurology