Antithrombotic action of recombinant hirudin in a venous thrombosis model.

The dose- and time-dependent antithrombotic activity of recombinant hirudin (r-hirudin) was examined in a new animal model of venous thrombosis. For the evaluation of the antithrombotic activity of r-hirudin, an occluding thrombus was produced by repeated clamping of the rat jugular vein. The number of clampings necessary to induce thrombosis served as a measure of antithrombotic activity. The gradual reduction of blood flow was registered by Doppler sonography. In order to estimate the relative antithrombotic activity of r-hirudin, its potency in this model was compared with other antithrombotic substances. r-Hirudin proved to be less potent than heparin after intravenous administration. Its half-life after subcutaneous administration was relatively short; however, the antithrombotic potency after subcutaneous administration was comparable to that of heparin.