Factor Xa inhibitors in clinical practice: Comparison of pharmacokinetic profiles

The anticoagulant actions of oral direct factor Xa (FXa) inhibitors can be inferred from their observed plasma concentrations; however, the steady-state pharmacokinetics (PK) of different FXa inhibitors have not been compared in clinically.

The sensitivity of the rivaroxaban, apixaban, and edoxaban in the STA-Liquid Anti-FXa assay were compared, and the anti-FXa plasma concentrations were measured for PK assessments. Nonlinear mixed-effects modeling was used to assess population PK in 329 patients with nonvalvular atrial fibrillation or venous thromboembolism. Patients were followed up for an average of 3.6 years.

Sensitivity was similar among the three drugs in this assay, which could directly compare plasma concentrations instead of anti-FXa activities. Overall exposure was greatest in 5 mg BID apixaban relative to other drugs (p < 0.001). The geometric mean AUC for the 0 to 24-h interval was 4550 ng h/mL for apixaban, 2710 ng h/mL for 15 mg QD rivaroxaban, and 1290 ng h/mL for 60 mg QD edoxaban. The PKs of 2.5 mg BID apixaban or 15 mg QD rivaroxaban were associated with hemorrhagic events.

Apixaban was associated with greater exposure, higher trough concentrations in plasma compared with rivaroxaban or edoxaban. Furthermore, a higher plasma concentration may partially predict hemorrhagic events.