Apixaban plasma concentrations in patients with obesity

Purpose Routine therapeutic drug monitoring of apixaban is currently not recommended but may however be warranted in some situations and for some patient groups to provide better and safer treatment. Due to limited data on apixaban concentrations in different subpopulations, it is still unclear which group of patients could possibly gain from monitoring. The purpose of this study was to examine apixaban exposure in patients with obesity compared with normal-weight patients. Methods Forty patients with obesity (mean BMI 39.4 kg/m 2 ) and 40 controls with normal weight (mean BMI 23.4 kg/m 2 ), treated with apixaban 5 mg twice daily were included. The patients were matched for age, sex, and renal function. Trough and peak apixaban concentrations were measured with LC‒MS/MS methodology. Results The median trough concentrations in patients with obesity (58.7, range 10.7–200.7 ng/ml) were slightly higher than those in patients with normal weight (52.0, range 31.0–150.9 ng/ml) ( p