Comparative study on the antithrombotic efficacy of hirudin, heparin and a low-molecular weight heparin in preventing experimentally induced venous thrombosis.

In a random, blind study, we compared the antithrombotic potential of unfractioned heparin, a low-molecular weight heparin (LMWH) and a recombinant hirudin (r-hirudin) given subcutaneously in a jugular vein thrombosis model in rabbits. All drugs and placebo were injected subcutaneously 2 h before inducing experimental thrombosis. A good thromboprophylactic effect was obtained with either LMWH and r-hirudin as compared with placebo. By contrast, no significant differences were found between groups in bleeding time. We also found a small (non-significant) prolongation of the activated partial thromboplastin time in the r-hirudin-treated animals. As for thrombin time, r-hirudin-treated rabbits exhibited too much sensitivity, with noncoagulable end-points. In our study, r-hirudin at the dose used seemed to be as effective as LMWH is in the prophylaxis of venous thrombosis.