Описание
Phenytoin induces CYP3A4-mediated metabolism of dexamethasone, significantly reducing dexamethasone plasma concentrations and risking loss of efficacy (e.g., in cerebral edema or cancer treatment).
Механизм
Phenytoin upregulates CYP3A4 and P-glycoprotein, markedly accelerating dexamethasone metabolism; dexamethasone AUC can fall by 50–80% during concurrent phenytoin therapy.
Клиническое значение
Clinical series in neuro-oncology and transplant patients document loss of dexamethasone efficacy (e.g., return of cerebral edema symptoms) within days of initiating phenytoin.
Тактика ведения
Double the dexamethasone dose when phenytoin is co-administered; monitor clinical response closely; consider levetiracetam as an alternative anticonvulsant to avoid this interaction.
Медицинский отказ от ответственности
This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making medication decisions.