BackgroundDue 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.ObjectivesTo 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.MethodsPatients with body weight >120 kg taking DOACs for any indication underwent a peak drug concentration measurement at steady state.Results38 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.ConclusionsMost 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.

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Anticoagulant-related nephropathy is an acute kidney injury (AKI) associated with excessive anticoagulation. The nature of the association between excessive anticoagulation with warfarin and AKI and its incidence remain unclear. To evaluate the incidence of AKI in excessively anticoagulated patients taking warfarin and examine potential risk factors. A retrospective chart review was performed in patients on chronic warfarin. The primary outcome was AKI, defined as an acute increase in creatinine of > 26.5 µmol/L within 7-14 days of an international normalized ratio (INR) ≥ 4.0. 292 patients with an INR ≥ 4.0 were included. 101 patients had CKD and 191 did not have CKD. Of the 292 patients with an INR ≥ 4.0, 38 (13%) had an AKI. In univariable analyses, CKD [odds ratio (OR) 2.1, 95% confidence interval (CI) 0.99-4.43] and use of renin-angiotensin system (RAS) blockers and/or diuretics (OR 3.85; 95% CI 1.15-20.15) were significantly associated with the risk of AKI. In a binomial logistic regression model, use of RAS blockers and/or diuretics was the only significant predictor of AKI (OR 3.4; 95% CI 1.02-11.76). Use of RAS blockers and/or diuretics significantly increased the risk of AKI in patients with warfarin-related excessive anticoagulation. Further prospective studies examining the association of high INRs and AKI are needed.