Fluctuations in anti-factor Xa levels with therapeutic enoxaparin anticoagulation in pregnancy.
OBJECTIVE
The objective of the study was to evaluate anti-factor Xa levels with therapeutic enoxaparin anticoagulation in pregnancy.


METHODS
A total of 15 pregnant subjects on therapeutic doses of enoxaparin (1 mg/kg +/-20% subcutaneously (s.c.) twice daily (b.i.d.)) were enrolled prospectively in this cross-sectional pilot project. Three blood levels for anti-factor Xa activity were examined: before the enoxaparin dose (trough), 3- to 4-h later (peak) and 8-h later. Anti-factor Xa activity level between 0.5 and 1.2 U/ml was considered therapeutic.


RESULTS
Mean anti-factor Xa activity levels were: trough 0.45+/-0.18, peak 0.9+/-0.25 and 8-h after dose 0.72+/-0.23 U/ml. All peak levels were therapeutic; 20% (3/15) of the 8 h and 73% (11/15) of the trough levels were sub-therapeutic.


CONCLUSIONS
Trough and 8-h post-dose anti-factor Xa activity levels were sub-therapeutic in a substantial number of patients receiving a b.i.d. regimen of therapeutic enoxaparin.
Friedrich
E
E
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Irvine, Orange, CA 92868, USA. efriedri@uci.edu
Hameed
A B
AB
D000328:Adult; D003430:Cross-Sectional Studies; D004334:Drug Administration Schedule; D016903:Drug Monitoring; D017984:Enoxaparin / Q000008:administration & dosage* / Q000032:analysis; D015951:Factor Xa / Q000032:analysis*; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006801:Humans; D007279:Injections, Subcutaneous; D010865:Pilot Projects; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000188:drug therapy*; D019851:Thrombophilia / Q000188:drug therapy*; D055815:Young Adult
D017984:Enoxaparin; D005343:Fibrinolytic Agents; D015951:Factor Xa