Inhibition of fluid phase and clot-bound thrombin by the thrombin exosite I ligand LU 58463: comparison with heparin and hirudin.

Heparin inhibits clot-bound thrombin less efficiently than fluid phase thrombin. We compared the ability of heparin, a non-selective indirect thrombin inhibitor, r-hirudin, a selective bifunctional thrombin inhibitor, and LU 58463, a non-catalytic exosite I thrombin inhibitor, to inhibit fluid-phase and clot-bound thrombin. The thrombin inhibitor LU 58463 was more effective than heparin and as effective as hirudin in inhibiting clot-bound thrombin.