Distribution of apixaban plasma concentrations across prescribed dose groups for ischemic stroke prevention in atrial fibrillation
K H Lim, J S Park, J Y Han, D H KimAbstract
Background
Apixaban is an oral anticoagulant used to prevent ischemic stroke in patients with non-valvular atrial fibrillation. However, the effects of dose reduction criteria on apixaban plasma concentrations in Korean patients remains unclear.
Methods
We performed a single-center laboratory study to evaluate plasma concentrations of apixaban prescribed in real-world clinical practice. Blood specimens were collected from the patients without missing or changing doses before sampling. Plasma concentrations were measured using anti-factor Xa chromogenic assays based on heparin liquid-reagent technology.
Results
We studied 284 patients across four prescribed-dose groups: standard dose (n = 204), on-label reduced dose (n = 47), off-label underdose (n = 29), and off-label overdose (n = 4). Peak and trough concentrations were higher in the standard group than the off-label underdose group. The proportion of apixaban’s peak concentrations within the expected 5th–95th percentile distribution range was higher in the off-label underdose group than the standard group (96.0 vs 77.8%, p = 0.023). Among patients receiving standard and on-label reduced dose, despite guideline-concordant prescribing, a substantial proportion of those aged ≥ 60 years, with body weight ≤ 80 kg, or with creatinine clearance 30–80 mL/min exhibited peak apixaban concentrations exceeding the upper limit of the expected reference range.
Conclusions
In Korean patients with atrial fibrillation, a subset receiving the standard or on-label reduced dose exhibited higher peak concentrations exceeding the upper limit of the expected ranges. Whereas, concentrations in the off-label underdose group, predominantly remained within the expected range.Distribution of apixaban concentrationsImpacts of each dose reduction criterion