Abstract 11598: Is Therapeutic Drug Monitoring of Direct Anticoagulants Really Unnecessary?

Introduction: no routine monitoring is deemed necessary with direct oral anticoagulants dabigatran (D) and rivaroxaban(R). Yet, their misuse may lead to inefficacy or increased risk of bleeding. Hypothesis: due to the prevalence of elderly patients in our medical center, the pharmacology department was asked to measure R and D plasma concentrations. Therefore we aimed not only to check their prescription adequacy but also to evaluate whether bleeding or thrombosis adverse events were associated with drug concentrations clearly outside of their expected “normal” range. Methods: Patients receiving R or D for either AFib, deep venous thrombosis or its prevention were included and had blood samples drawn for drug measurements, by HPLC-tandem mass spectrometry. Adequacy of the patient prescription was checked by pharmacists according D & R respective SmPCs. A robust and conservative method was applied to evaluate anticoagulant concentrations : D & R concentrations were blindly deemed “normal” when within the [...