Effect of therapeutic plasma exchange on the anti–factor Xa activity of enoxaparin: A case report

PURPOSE: A case is reported in which the anti-factor Xa activity of enoxaparin was measured during therapeutic plasma exchange (TPE). SUMMARY: A 52-year-old male underwent TPE for antineutrophil cytoplasmic antibody-associated vasculitis while receiving therapeutic enoxaparin. Enoxaparin anti-factor Xa levels were measured before and immediately after TPE sessions as well as outside TPE sessions. The calculated enoxaparin half-life during TPE was 0.897 hours, whereas the calculated half-life outside TPE was 5.26 hours, demonstrating that the half-life of enoxaparin is dramatically shortened during TPE. CONCLUSION: Enoxaparin's anti-factor Xa activity should be monitored and dosing schedules should be adjusted to ensure therapeutic enoxaparin levels in all patients receiving TPE.