Managing the Drug-Drug Interaction With Apixaban and Primidone: A Case Report.

The management of the drug-drug interaction (DDI) between primidone, a moderate to strong cytochrome P-450 (CYP) 3A4 inducer, and apixaban, a direct oral anticoagulant (DOAC) and CYP3A4 substrate is complex and limited evidence exists to guide management. This case report describes a 65-year-old male, receiving primidone for essential tremor who developed an acute venous thromboembolism (VTE) requiring oral anticoagulation. DOACs are preferred over vitamin K antagonists for acute VTE treatment.