Moderate
Established
Description
Phenytoin reduces topiramate plasma levels via enzyme induction, potentially compromising seizure control when topiramate is added to phenytoin therapy.
Mécanisme
Phenytoin is a potent CYP3A4 and CYP2C19 inducer that increases topiramate metabolic clearance by approximately 48%.
Signification clinique
Topiramate levels may be halved by phenytoin co-administration; dose adjustments are typically required to maintain therapeutic effect.
Prise en charge
Monitor seizure control and topiramate levels; titrate topiramate to therapeutic effect with awareness of enhanced clearance.