Kinetic analyses showed that a ""normal"" FX concentration of approximately 140 nM in plasma did not induce maximum catalytic efficacy of FVIIa and that an increase in the concentration of FX in hemophilic plasma enhanced the thrombin generation potential of FVIIa. Thus, the FVIIa/FX mixture was prepared by assembling plasma-derived FVIIa and FX at a weight ratio of 1:10. The FVIIa/FX mixture proved superior to rFVIIa with regards to shortening the APTT and accelerating the thrombin generation in hemophilic plasma. The FVIIa/FX mixture promoted the generation of thrombin more than did rFVIIa.
Increasing the FX concentration in hemophilic plasma gives a higher clotting potential of FVIIa. A FVIIa/FX concentrate may serve as a new alternative bypassing agent.