RECOMBINANT HUMAN FACTOR VIIA (RFVIIA) IN A RABBIT STASIS MODEL

The thrombogenicity of recombinant human FVIIa (rFVIIa) and FEIBA was studied in a rabbit stasis model. Only minor thrombus formation in isolated vein segments during 10 min. of stasis was seen following the administration of rFVIIa 100-1000-mu-g/kg or FEIBA 50-100 U/kg whereas both compounds caused clear thrombus formation during 30 min. of stasis. RFVIIa caused no change in platelet counts or plasma fibrinogen 3 hours after administration, whereas a small decrease of APTT was seen due to the direct effect of rFVIIa in this assay. In contrast, FEIBA caused a significant and dose-dependent decrease of platelet counts as well as of fibrinogen, and an increase of APTT which demonstrate a general consumption of coagulation factors. In conclusion the study demonstrated a local pharmacological effect of rFVIIa in the absence of a general activation of the coagulation cascade.