Topiramate–phenytoin

Topiramate–phenytoin does not represent a single biological target or receptor; rather, it describes a clinically significant drug-drug interaction between two antiepileptic medications (StatPearls, NBK554527). Topiramate is a sulfamate-substituted monosaccharide that acts on multiple targets, including voltage-gated sodium channels, GABA-A receptors, and carbonic anhydrase (PubMed, PMID: 10403561). Phenytoin is a hydantoin derivative that primarily stabilizes neuronal membranes by blocking voltage-gated sodium channels in their inactive state (StatPearls, NBK551520). When co-administered, phenytoin acts as a potent inducer of the CYP3A4 enzyme, which can lead to a significant reduction in topiramate plasma concentrations (Drugs.com). Conversely, topiramate has been shown to inhibit the CYP2C19 isoenzyme, which may result in increased serum phenytoin levels and potential toxicity in some patients (PubMed, PMID: 9169032). This interaction necessitates careful therapeutic drug monitoring and dosage adjustments to maintain seizure control and avoid adverse effects.

Other names

Topiramate and phenytoin interactionPhenytoin-topiramate combination

Pharmacokinetic drug-drug interaction involving CYP3A4 induction by phenytoin and CYP2C19 inhibition by topiramate.