Veyvondi

von Willebrand factor (VWF) is the carrier molecule for factor VIII (FVIII), an essential cofactor of secondary haemostasis that leads to the fibrin clot formation, and facilitates platelet adhesion to sub-endothelium at sites of vascular injury.Vonicog alfa is a recombinant human von Willebrand factor (rVWF). Vonicog alfa behaves in the same way as endogenous VWF.Administration of vonicog alfa allows correction of the haemostatic abnormalities exhibited by patients who suffer from VWF deficiency (VWD) at two levels: Vonicog alfa re-establishes platelet adhesion to the vascular sub-endothelium at the site of vascular damage (as it binds both to the vascular sub-endothelium matrix (for example, collagen) and to the platelet membrane), providing primary haemostasis as shown by the shortening of the bleeding time. This effect occurs immediately and is known to depend to a large extent on the level of polymerisation of the protein. Vonicog alfa produces delayed correction of the associated FVIII deficiency. Administered intravenously, vonicog alfa binds to endogenous FVIII (which is produced normally by the patient), and by stabilising this factor, avoids its rapid degradation. Because of this, administration of vonicog alfa restores the FVIII:C level to normal as a secondary effect. After the first infusion, the FVIII:C rises above 40% within 6 hours and peaks within 24 hours in a majority of patients, depending on the baseline FVIII:C level. The adhesive activity of rvWF depends on the size of its multimers, with ultra-large multimers being the most effective in supporting interactions with collagen and platelet receptors.