Peak plasma concentration of direct oral anticoagulants in obese patients weighing over 120 kilograms: A retrospective study

Due to a paucity of data on the efficacy and safety of direct oral anticoagulants (DOACs) in patients with a body mass index >40 kg/m2 or a weight >120 kg, the use of DOACs in this group is not recommended.To determine the proportion of obese patients with body weight >120 kg with a peak plasma concentration of DOACs lower than the expected median trough level derived from population pharmacokinetic studies for each DOAC.Patients with body weight >120 kg taking DOACs for any indication underwent a peak drug concentration measurement at steady state.38 patients were included in the analysis. The mean age was 64 ± 11 years, and 30 (79%) were males. The median body weight was 132.5 kg (interquartile range [IQR] 127-146.5). The median peak concentrations (IQR) were 148 ng/mL (138-240), 138 ng/mL (123-156.5), 215 ng/mL (181-249) for apixaban, dabigatran, and rivaroxaban, respectively. Two patients (5%, 95% confidence interval [CI]: 0.5%-18%) had a peak plasma concentration lower than the median trough and eight (21%, 95% CI: 11%-37%) had a peak plasma concentration below the fifth percentile (10th percentile for dabigatran) peak concentration.Most patients in our study had peak plasma concentration higher than the median trough level for each of the three DOACs. However, 21% had a peak plasma concentration that was below the usual on-therapy range of peak concentration for the corresponding DOAC.