Abstract
BACKGROUND: Chromogenic anti-factor Xa activity (AXA) assay is used to measure the pharmacodynamics of factor Xa inhibitors, including edoxaban. Although AXA concentrations in patients with non-valvular atrial fibrillation using edoxaban have been reported, the impact of renal function on AXA concentrations with edoxaban use in patients with non-valvular atrial fibrillation has not been fully assessed. METHODS: Trough and peak AXA concentrations were measured in 93 patients with non-valvular atrial fibrillation taking edoxaban (73.6 ± 11.2 years, 48 were male). The patients were divided into three groups: patients with moderate renal dysfunction (creatinine clearance 15-49 mL/min), mild renal dysfunction (creatinine clearance 50-95 mL/min), and normal renal function (creatinine clearance > 95 mL/min). Both trough and peak AXA concentrations were assessed among the groups according to the edoxaban dose (30 or 60 mg). RESULTS: At a 30-mg dose, patients with moderate renal dysfunction showed significantly higher trough AXA concentrations than patients with mild renal dysfunction or normal renal function. At a 60-mg dose, patients with mild renal dysfunction showed significantly higher trough AXA concentrations than patients with normal renal function. Peak AXA concentrations were not significantly different between the groups. Creatinine clearance was significantly and negatively correlated with trough AXA concentrations at a 60-mg dose, whereas the correlation of creatinine clearance with AXA concentrations was borderline significant at a 30-mg dose. No correlation was found between creatinine clearance and peak AXA concentrations at either dose. CONCLUSIONS: Creatinine clearance tends to be negatively correlated with trough AXA concentrations in patients with non-valvular atrial fibrillation taking edoxaban, while renal function is not correlated with peak AXA concentrations.