Anti Xa activity and prothrombinase inhibition in patients treated with two different doses of enoxaparin in gynecologic surgery.
A prospective open study was performed in a series of 547 patients undergoing gynecologic surgery. A dose of 20 mg of enoxaparin was administered to all patients 2 hours before surgery. Then patients at high risk of thrombosis (mostly oncologic surgery) received 40 mg of enoxaparin daily whereas those at moderate risk received 20 mg of enoxaparin daily. The principal aim of this prospective open study was to monitor amidolytic anti Xa activity and to study the inhibition of intrinsic prothrombinase using prothrombin consumption measurement as a simple and global test. A second aim was to investigate efficacy and tolerance of these regimens. Treatment tolerance was satisfactory with both regimens since the total incidence of bleeding was 1.8%. A single patient developed a clinically significant thrombosis during hospital stay. The results confirm and extend previous reports regarding a dose effect relationship between the dose of Enoxaparin and plasma Anti Xa activity 3 hours after s.c. injection. A significant relationship was found between Anti Xa activity and patients body weight. Interestingly a dose dependent inhibition of intrinsic prothrombinase was observed when using a one stage prothrombin consumption assay in whole blood. This test in whole blood can be considered as closer to physiological conditions than assays performed in citrated platelet rich or platelet poor plasma samples. The mechanism of intrinsic prothrombinase inhibition during prophylactic treatment with enoxaparin requires further investigation.
Samama
M M
MM
Laboratoire Central d'Hématologie, Hôtel-Dieu, Paris.
Combe
S
S
Horellou
M H
MH
Augras
D
D
Truc
J B
JB
Conard
J
J
Girard
P
P
Bara
L
L
Poitout
P
P
D000328:Adult; D001835:Body Weight; D004305:Dose-Response Relationship, Drug; D065427:Factor Xa Inhibitors; D005260:Female; D005831:Genital Diseases, Female / Q000601:surgery*; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007279:Injections, Subcutaneous; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011183:Postoperative Complications / Q000517:prevention & control*; D011446:Prospective Studies; D011516:Prothrombin / Q000378:metabolism; D012307:Risk Factors; D013923:Thromboembolism / Q000517:prevention & control*; D013925:Thromboplastin / Q000037:antagonists & inhibitors*
D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D011516:Prothrombin; D013925:Thromboplastin