Lisman T, Bijsterveld NR, Adelmeijer J, Meijers JC, Levi M, Nieuwenhuis HK, De Groot PG, Recombinant factor VIIa reverses the in vitro and ex vivo anticoagulant and profibrinolytic effects of fondaparinux. J Thromb Haemost 2003;1:2368-73.
The authors reported the in vitro and ex vivo effects of rFVIIa on clot formation and thrombin-activatable fibrinolysis inhibitor (TAFI)-mediated down-regulation of fibrinolysis after fondaparinux administration using in vitro clot lysis assays were performed in pooled normal plasma from healthy volunteers to which fondaparinux was added, and in serial samples from healthy volunteers who received a single bolus dose of fondaparinux, a single bolus dose of rFVIIa, or both. Fondaparinux significantly delayed clot formation, and clot lysis was significantly increased due to decreased activation of TAFI. Addition of recombinant FVIIa corrected the inhibited clot formation induced by fondaparinux, and the acceleration of clot lysis was partially reversed. In vivo administration of fondaparinux (10 mg) to healthy volunteers similarly resulted in accelerated plasma clot lysis. Subsequent administration of rFVIIa (90 micro g kg-1) normalized the clot lysis time up to 6 h post administration. The authors suggest rFVIIa might be a good therapeutic option in patients treated with fondaparinux who develop bleeding complications, since both clot formation as well as fibrinolytic resistance are improved.