Clinical and Pharmacological Effects of Apixaban Dose Adjustment in the ARISTOTLE Trial

In the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial, patients with atrial fibrillation and ≥2 dose-adjustment criteria (age ≥80 years, weight ≤60 kg, or creatinine ≥1.5 mg/dl [133 μmol/l]) were randomized to receive apixaban 2.5 mg twice daily or warfarin. The purpose of this study was to describe the effects of apixaban dose adjustment on clinical and pharmacological outcomes. Patients receiving the correct dose of study drug were included (n = 18,073). The effect of apixaban 2.5 mg twice daily versus warfarin on population pharmacokinetics, D-dimer, prothrombin fragment 1 + 2 (PF1+2), and clinical outcomes was compared with the standard dose (5 mg twice daily). Patients receiving apixaban 2.5 mg twice daily exhibited lower apixaban exposure (median area under the concentration time curve at a steady state 2,720 ng/ml vs. 3,599 ng/ml; p