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Updated: Jun 11, 2026

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Injection of recombinant activated factor VII can induce transient increase in circulating procoagulant
Valérie Proulle1, Bénédicte Hugel, Benoit Guillet
1INSERM Unit 143, Hôpital Bicêtre, Le Kremlin Bicêtre, France. proulle@kb.inserm.fr
Abstract:
Recombinant activated factor VII (rFVIIa) is an effective haemostatic treatment in haemophiliacs with inhibitors. In vitro, FVIIa concentrations corresponding to those obtained with therapeutic doses of rFVIIa have been shown to induce normal thrombin generation and platelet activation in the absence of factors VIII or IX. To further study the in vivo haemostatic changes induced by rFVIIa, circulating procoagulant microparticles (MP) were measured in patients treated with discontinuous injections of Novoseven. In 6 out of 15 patients, a transient peak of procoagulant MP was observed after injection, occurring 15 min to 2 h after infusion. It was composed primarily of platelet-derived MP and was of very short duration. This peak was not observed in haemophiliacs without inhibitor, who were treated with conventional replacement therapies. Our results provide further in vivo evidence that rFVIIa specifically activates platelets, either directly or as a consequence of a burst of thrombin generation that could account for its haemostatic efficacy.
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