# Tailoring Anticoagulant Therapy: Managing Interactions Between Carbamazepine and Direct Oral Anticoagulants (DOACs)

## TL;DR

This case study shows how to manage anticoagulation in a patient on carbamazepine who cannot use injectable or standard oral anticoagulants.

## Contribution

Presents a novel approach using edoxaban with monitoring for patients on carbamazepine and unable to use standard anticoagulants.

## Key findings

- Edoxaban was safely used in a patient on carbamazepine with therapeutic drug levels confirmed.
- The patient remained stable without thrombotic or bleeding complications.
- Plasma level monitoring and close follow-up are essential for this combination.

## Abstract

Standard prophylaxis after hip surgery typically involves parenteral anticoagulation. However, this approach may not be feasible for patients with significant comorbidities or barriers to injectable treatments. Oral anticoagulants can be considered, but vitamin K antagonists present compliance concerns, and many direct oral anticoagulants (DOACs) are limited by drug interactions.

A 61-year-old male care home resident with multiple comorbidities, including hypoxic brain injury-related seizures and a severe needle phobia, underwent right hip hemiarthroplasty after sustaining a femoral neck fracture. Parenteral thromboprophylaxis was not a viable option due to the needle phobia, and vitamin K antagonists were excluded because of adherence concerns. The patient's regular use of carbamazepine, a strong enzyme inducer, further complicated anticoagulant selection due to its potential to reduce DOAC effectiveness. After a multidisciplinary review, edoxaban was chosen as the most suitable option.

The patient was managed with a daily regimen of edoxaban 60 mg, with therapeutic drug levels confirmed through monitoring. He remained clinically stable without thrombotic or bleeding complications.

This case highlights the importance of an individualised approach to anticoagulation in complex patients, where both clinical context and drug interactions must be carefully considered and balanced. Edoxaban may represent a feasible strategy in patients receiving carbamazepine, provided that treatment is supported by plasma level monitoring and close follow-up.