Factor Xa Inhibitor Plasma Concentrations and Clinical Outcomes in Patients Weighing ≤50 kg—Experience from Four UK Centers

In recent years, factor Xa inhibitor (FXaI) research at the extremes of bodyweight has focused on obesity (>120 kg), but significant gaps in clinical outcome data and pharmacokinetic studies exist in those weighing ≤50 kg.[1] [2] In low bodyweight (LBW), the concern is of over-exposure and an increased risk of bleeding. Clinicians are increasingly challenged with this vulnerable population, due to a growing older adult population and with FXaIs more frequently prescribed in patients with cancer. We set out to describe experience from four UK centers on the use of FXaIs in LBW patients (≤50 kg) including a summary of patient characteristics, FXaI plasma concentrations, and clinical outcomes during the first 90 days of treatment.