Management and monitoring of recombinant activated factor VII

Recombinant factor VIIa (rFVIIa) has recently been introduced as a new 'byp assing' agent to improve haemostasis in haemophilia patients with inhibitor s to factor (F) VIII or FIX. In noninhibitor patients, levels of circulatin g FVIII or FIX can be used to assess the quality of substitution therapy. I n contrast, laboratory monitoring of haemostatic efficacy in patients treat ed with rFVIIa has proved more complex. Evaluation of patient samples saved during rFVIIa treatment have revealed some correlation between FVII:C leve ls and improved haemostasis, while whole blood elasticity as determined by thromboelastography, has been shown to improve following rFVIIa treatment. The investigation aimed to study the efficacy of rFVIIa in activating FX:C and in shortening the whole blood clotting time (WBCT) using the newly-deve loped roTEG coagulation instrument. Results indicated a substantial and app arently dose-dependent activation of FX:C by rFVIIa. In addition, the prese nce of FIX appeared to influence FX:C activation. In-vitro and ex-vivo roTE G thromboelastograph measurements showed that FVIIa shortened WBCT; althoug h normalization did not occur. The results presented here are based on a sm all number of observations in a few patients and further studies should be planned to test the efficacy of these monitoring principles in clinical tre atment practice with rFVIIa. Blood Coagul Fibrinolysis 11 (suppl 1):S25-S30 (C) 2000 Lippincott Williams & Wilkins.