Peak antifactor Xa activity produced by dalteparin treatment in patients with renal impairment compared with controls

Study Objective. To evaluate the relationship between impaired renal function and antifactor Xa activity in patients receiving dalteparin. Design. Open-label prospective study. Setting. Inpatient and outpatient units of a large teaching hospital. Subjects. Eleven patients with renal impairment and 11 control subjects with normal renal function. Intervention. Subjects were administered dalteparin at a dosage of approximately 100 U/kg subcutaneously every 12 hours. Measurements and Main Results. Peak steady-state antifactor Xa levels were compared between the groups. Mean ± SD levels were similar for patients with and without renal impairment: 0.47 ± 0.25 and 0.55 ± 0.20 U/ml, respectively. A test of equivalency showed statistical significance (p=0.0001). Conclusion. No meaningful difference in peak antifactor Xa activity was found between patients with renal impairment and control subjects. To the extent that peak antifactor Xa levels can be used as markers for adjusting doses of dalteparin, these data suggest that such adjustments are not necessary for patients with renal impairment who are not receiving dialysis.