Synthesis and comparison of tripeptidylfluoroalkane thrombin inhibitors.

Fluorinated ketone thrombin inhibitors based on the peptide sequence methyl-(D)-Phe-Pro-Arg-CF2R were synthesized: MDL 73,446 (1, R = F); MDL 73,775 (2, R = CF3); and MDL 75,579 (3, R = CH2CH2CH3). These were shown to be highly effective, slow binding inhibitors of thrombin. Anticoagulant activity was dose-dependent with 3 > 2 > 1 at doubling thrombin time and APTT, respectively. Anticoagulant activity corresponded with efficacy in a platelet-dependent (FeCl3-induced) rat carotid artery thrombosis model. Arterial occlusion was dose-dependently prolonged with 3 > 2 > 1 at doubling the occlusion time.