Effect of low molecular weight heparin on coagulation parameters and bleeding time in healthy volunteers

In a randomized intraindividual cross-over study 8 healthy volunteers received subcutaneously 1500 IU, 2000 IU and 25,00 IU, respectively, of low molecular weight heparin (LMWH) in 24-h intervals, as well as 12-hourly 3 applications of 5000 IU of unfractionated heparin. The wash-out phases between the different medications lasted 7 days each. The course of the activated partial thromboplastin time showed no difference between the medications given, whereas the inhibition of factor Xa was significantly stronger after application of all dosages of LMWH than after unfractionated heparin injections. Bleeding time was prolonged only under 1500 IU of LMWH as compared to heparin. Neither LMWH nor unfractionated heparin caused an influence on the antithrombin III levels.