Major
Apixaban × Carbamazepine
Direct oral anticoagulants (factor Xa inhibitors)×Antiepileptics. Carboxamide derivatives
Mechanism
Carbamazepine induces CYP3A4 and P-glycoprotein – two apixaban clearance routes. Apixaban plasma levels fall and antithrombotic effect weakens.
Symptoms
The patient feels nothing. Stroke risk in atrial fibrillation rises, as do deep vein thrombosis and pulmonary embolism risks.
Management
Avoid the combination. Alternative anticoagulants: warfarin with INR monitoring or low molecular weight heparin. Alternative anticonvulsants without induction: levetiracetam, lamotrigine.