Introduction: Enoxaparin is an anticoagulant used in the treatment of thromboembolic diseases. It is a hydrophilic molecule that is, predominantly, eliminated renally with few data to support dosing for subjects with renal impairment and/or obesity. A recently conducted randomized controlled clinical trial compared individualized enoxaparin doses based on lean body weight and renal function to conventional dosing. During this trial, anti-Xa concentrations were collected using a sparse sampling design and a population pharmacokinetic model was developed to describe the data.
Methods: The current study evaluated the ability of the individualized dose to achieve and maintain anti-Xa concentrations within the therapeutic range (0.5-1.0 IU/mL) in subjects with renal impairment and/or obesity. A matched comparison of the two dosing strategies was undertaken using individual model predicted anti-Xa concentrations generated every 30 minutes to 120 hours post initiation of therapy. Concentration-time curves were generated for each subject and the proportion of time in the therapeutic, supratherapeutic, and subtherapeutic ranges were determined.
Results: When compared with conventional dosing, individualized dosing in subjects with renal impairment resulted in a significantly greater proportion of time in the therapeutic range (median [range] = 69.9% (11.3-91.8) versus 42.6% [13.9-71.4], P = 0.02) and a significantly reduced proportion of time in the supratherapeutic range (median [range] = 9.3% (0%-67.0%) versus 37.1% (0%-85.7%), P = 0.02). Although there was a trend toward a greater proportion of time in the therapeutic range in obese subjects, this did not achieve statistical significance.
Conclusions: Individualized dosing in subjects with renal impairment is more effective than conventional dosing at achieving and maintaining therapeutic anti-Xa concentrations, which could decrease the risk of bleeding events and mortality in these subjects.