Low molecular weight heparin Novo (LHN-1) does not cross the placenta during the second trimester of pregnancy.
Unfractionated heparin (UF-H) has been the drug of choice for the treatment of thromboembolic disorders during pregnancy. Low molecular weight heparin (LMW-H) preparations may present some advantages over UF-H. They have longer half-lives and a better bioavailability after subcutaneous (s. c.) injection and may cause less bleeding. It has not yet been established whether LMW-H Novo (LHN-1) crosses the placenta. 17 women admitted for abortion during the second trimester of pregnancy (induced by application of prostaglandine PGE2 gel at a concentration of 0.25 mg/ml into the cervix) were given s. c. 35 anti-Xa units per kg of body weight of LHN-1 (Novo). 10 patients not receiving LHN-1 and their fetuses served as a control group. 7 women in whom the time interval between injection of LHN-1 and expulsion of the fetus was less than 3 h or more than 7 h were excluded from further study. In one fetus blood collection failed. Anti-Xa and anti-IIa levels increased approximately ten-fold in women receiving LHN-1 [anti-Xa units/ml from 0.02 +/- 0.01 (mean +/- SD) to 0.17 +/- 0.01, p less than 0.001; anti-Ha units/ml from less than 0.01 +/- 0.01 to 0.07 +/- 0.03], but remained below the detection limit in their fetuses as well as in the women and fetuses of the control group. We conclude that LHN-1 at these doses does not cross the placenta during the second trimester of pregnancy to suggest that LHN-1 may be a safe alternative to heparin in the management of the thromboembolic complications during pregnancy.
Omri
A
A
Department of Medicine, CHUV, Lausanne, Switzerland.
Delaloye
J F
JF
Andersen
H
H
Bachmann
F
F
D000028:Abortion, Induced; D000293:Adolescent; D000328:Adult; D015951:Factor Xa; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D006495:Heparin, Low-Molecular-Weight / Q000493:pharmacokinetics*; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011516:Prothrombin / Q000037:antagonists & inhibitors; D015842:Serine Proteinase Inhibitors
D006495:Heparin, Low-Molecular-Weight; D015842:Serine Proteinase Inhibitors; D011516:Prothrombin; C025337:Factor IIa; D015951:Factor Xa