In this study, the in-vitro fibrinolytic efficacy of Tenecteplase, Amediplase and scu-PA was investigated in different external lysis models by measuring the lysis of human plasma clots after the addition of the plasminogen activators (PAs) to the surrounding plasma. The effect of TAFI was examined for each PA by neutralising TAFIa with potato carboxypepticlase inhibitor (PCI). The lytic efficacy of Amediplase was lower than that of Tenecteplase at low PA concentrations but slightly higher at therapeutic concentrations. The activity of scu-PA was clearly lower than that of either Tenecteplase or Amediplase. The TAFI system inhibited external clot lysis mediated by all the PAs when thrombo-modulin was present in the model. In the therapeutic range (5-10 μg/ml) however, the TAFIa effect was negligible for both Amediplase and Tenecteplase. At lower PA concentrations the effect of TAFI on Amediplase was slightly stronger than that on Tenecteplase. Under static conditions the lysis rates were lower than with stirring.The role of TAFI was similar under both conditions. In conclusion, at therapeutic concentrations Amediplase was slightly more active than Tenecteplase and scu-PA under all conditions used. Therefore, Amediplase might possibly be a more potent thrombolytic agent at these concentrations and increase the efficacy of thrombolysis. The potential of TAR for inhibiting thrombolytic therapy is probably low. However in conditions where the local PA concentrations are sub-optimal TAFI might affect the lysis rate? © 2006 Schattauer GmbH, Stuttgart. Chemicals / CAS: amediplase, 151912-11-7; carboxypeptidase, 9031-98-5; plasminogen activator, 9039-53-6; prourokinase, 82657-92-9; tenecteplase, 191588-94-0; thrombomodulin, 112049-68-0; amediplase, 151912-11-7; Carboxypeptidase U, EC 3.4.17.20; Carboxypeptidases, EC 3.4.-; Fibrin, 9001-31-4; Fibrinolytic Agents; Plasminogen Activators, EC 3.4.21.-; tenecteplase; Tissue Plasminogen Activator, EC 3.4.21.68; Urinary Plasminogen Activator, EC 3.4.21.73.