Effect of Plasmapheresis on the Anti-Factor Xa Activity of Enoxaparin in an Obese Adolescent Patient.
To our knowledge, the effect of plasmapheresis on the anti-factor Xa activity of enoxaparin has never been reported. We describe a 13-year-old, obese (92-kg) girl who was treated with enoxaparin for a pulmonary embolism while receiving plasmapheresis for suspected autoimmune encephalitis and who experienced clinically significant reductions in anti-factor Xa activity after plasmapheresis. She received five courses of plasmapheresis, with the final two administered during treatment with enoxaparin. Her anti-factor Xa concentrations were highly variable, and we hypothesized that plasmapheresis was affecting these levels. To test this hypothesis, anti-factor Xa concentrations were measured before and immediately after the patient's last plasmapheresis treatment, and then again 2 days after plasmapheresis. The rate of anti-factor Xa activity decline was 0.28 IU/mL/hour with plasmapheresis and only 0.088 IU/mL/hour on the day without plasmapheresis, representing a greater than 3-fold difference. The changes in anti-factor Xa activity due to plasmapheresis altered the final enoxaparin dosage required to remain in the therapeutic range of 0.5-1 IU/mL (0.98 mg/kg/dose while receiving plasmapheresis vs 0.69 mg/kg/dose without plasmapheresis). Our patient's data suggest that plasmapheresis can significantly alter enoxaparin's anticoagulant effect as measured by anti-factor Xa concentrations, which could cause a decreased anticoagulant effect during plasmapheresis and an increased risk of bleeding on plasmapheresis discontinuation. If concurrent enoxaparin-based anticoagulation and plasmapheresis are necessary, close monitoring of anti-factor Xa levels is advisable. Dose escalations and reductions of enoxaparin may be necessary when initiating and discontinuing plasmapheresis, respectively.
Virginia Commonwealth University School of Pharmacy, Richmond, Virginia.
Kassim W
KW
Rahawi
Virginia Commonwealth University School of Pharmacy, Richmond, Virginia.
Kristi L
KL
Higgins
Virginia Commonwealth University School of Pharmacy, Richmond, Virginia.|Department of Pharmacy Services, Virginia Commonwealth University Health, Richmond, Virginia.
Cady
C
Noda
Virginia Commonwealth University Health, Richmond, Virginia.|Department of Pharmacotherapy and Outcomes Science, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia.
Jeremy S
JS
Stultz
D000293:Adolescent; D017984:Enoxaparin / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D015951:Factor Xa / Q000378:metabolism; D065427:Factor Xa Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D063766:Pediatric Obesity / Q000150:complications*; D010956:Plasmapheresis; D011655:Pulmonary Embolism / Q000188:drug therapy
D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D015951:Factor Xa
anti-N-methyl-d-aspartate receptor encephalitis; blood coagulation factors; enoxaparin; factor Xa; low-molecular-weight heparin; plasmapheresis; pulmonary embolism