Patent ID: 7625866

Claim:
A process for producing a concentrate of a factor VIII:C-containing von Willebrand factor (vWF/FVIII:C), comprising subjecting a liquid comprising factor VIII:C (FVIII:C) and von Willebrand factor (vWF) to a fractional precipitation using an effective amount of at least one of an alkali metal salt or an alkaline earth metal salt, and an amino acid chosen from glycine, α- or β-alanine, α- or β- or γ-aminobutyric acid, lysine, valine, asparagine, and glutamic acid, wherein the fractional concentration of the amino acid is from about 67 to about 110 g/l, such that the produced concentrate has an increased content of high molecular weight multimers of vWF, and a ratio of von Willebrand factor ristocetin cofactor activity (vWF:RCoF) to von Willebrand factor antigen (vWF:Ag) of greater than 1.