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