Safety and efficacy of a low molecular weight heparin (Logiparin) versus dextran as prophylaxis against thrombosis after total hip replacement.

In order to study the plasma levels of factor XaI and IIaI activity an enzymatically depolymerized low molecular weight heparin (LMW-heparin; Logiparin) was given s.c. in a dose of 35 XaI mu/kg b.w. once daily for 7 days to 10 patients undergoing total hip replacement (THR) in a pilot study. The XaI activity was less than or equal to 0.24 XaI units/ml and the IIaI activity less than or equal to 0.043 IIaI mu/ml. No accumulation of the activities were seen. No phlebographically verified thrombi or any bleeding complications were registered. From this study it was concluded that the given dose of Logiparin was safe with regard to bleeding complications. Based on these data, an open, randomized controlled trial was started. In this main study the thromboprophylactic effect of the LMW-heparin (Logiparin) in a dose of 35 XaI mu/kg b.w. once daily was compared with that of dextran 70 in patients undergoing THR. 100 patients were randomized. The over-all thrombosis rate was 28% in patients treated with LMW-heparin and 39% in those given dextran, a non-significant difference. No bleeding complications, deaths or pulmonary embolism were recorded in either group. Peroperative blood loss and transfusion requirements were similar in the two groups. In conclusion, the investigated LMW-heparin (Logiparin) is safe and effective in preventing postoperative thromboembolism in patients undergoing total hip replacement, but the dosage can probably be optimized.