Deskripsi

Phenytoin and warfarin have a complex bidirectional interaction: phenytoin initially inhibits warfarin metabolism (raising INR) but then induces it (lowering INR), making anticoagulation management unpredictable.

Mekanisme

Acute phenytoin administration inhibits CYP2C9; with chronic use, CYP2C9 induction predominates, increasing warfarin clearance. Warfarin may displace phenytoin from albumin and inhibit its metabolism.

Signifikansi Klinis

Both bleeding (early) and thromboembolic (late) events have occurred; warfarin can also raise phenytoin levels, risking phenytoin toxicity.

Penatalaksanaan

Monitor both INR and phenytoin levels frequently when initiating, adjusting, or stopping either drug. Consider alternative anticonvulsants.

Penyangkalan Medis

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.

Data sources: ChEMBL, PubChem, DailyMed.