Major
Established
Description
Carbamazepine markedly reduces warfarin plasma concentrations, potentially resulting in sub-therapeutic anticoagulation and increased thromboembolic risk.
Mécanisme
Carbamazepine is a potent inducer of CYP2C9 and CYP3A4, the primary enzymes responsible for warfarin metabolism, accelerating its clearance.
Signification clinique
INR can drop significantly; thrombotic events (stroke, PE) have been reported when warfarin doses were not increased proportionally.
Prise en charge
Monitor INR closely when initiating or stopping carbamazepine; warfarin dose increases of 50–100% may be required. Consider alternative anticonvulsants if feasible.