[Low molecular weight heparins in everyday practice].
Standard nonfractioned heparin has been used for fifty years in the treatment of thromboembolic accidents, and for fifteen years, since Kakkar's works, in the prevention of thromboembolic complications in a surgical and medical context [5]. The antithrombotic efficacy of nonfractioned heparin (NFH) is accompanied by hemorrhagic complications occurring in about 10% of the patients receiving a "curative" treatment at hypocoagulating doses and in about 5% of the patients receiving the low-dose "preventive" treatment. The interest raised by low molecular weight heparins (LMWH), prepared as early as 1970, was based on a concept that is currently called into question: their anti-Xa activity, accounting for the antithrombotic activity, is high, while the anti-IIa (antithrombin) activity, producing the hemorrhagic risks, is lower. The pharmacokinetic properties, including longer-lasting action and better bioavailability with subcutaneous delivery relative to standard heparin, have greatly facilitated their use in the clinical field by allowing the reduction of the daily number of injections. Extensive clinical trials have confirmed that the antithrombotic efficacy of the LMWH is at least equal, if not superior, to that of nonfractioned heparin, though without reducing the frequency of hemorrhagic complications in the prevention of postoperative phlebitis. A limited number of randomized clinical trials suggests that the LMWH might also be as effective as NFH, as expected at doses about 3 times as high as those used for prophylaxis.
Horellou
M H
MH
Laboratoire central d'Hématologie, Hôtel Dieu de Paris.
Samama
M
M
D006495:Heparin, Low-Molecular-Weight / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D013924:Thrombophlebitis / Q000188:drug therapy* / Q000517:prevention & control
D006495:Heparin, Low-Molecular-Weight
Les héparines de bas poids moléculaire en pratique courante.