[Contribution to the mechanism of the "factor VIII bypassing activity" (FEIBA)-reaction].

The principle of the FEIBactivity hadn't been defined in a sufficient manner up to now. Probably the factor VII or factor VIIa are playing a key role. According to own experiments the factor VII activity increases considerably in activated prothrombincomplex concentrates together with the quotient factor VIIa/VII. Factor VII should be administered in his activated form for bypassing. Fractions with limitation of the activation process to factor VII are of a low thrombogenicity. Among activated coagulation factors factor VIIa persists longest in the circulation and a bypass efficacy can be provoked only by this.