Von Willebrand Factor (VIIIVWF) in lyophilized Factor VIII concentrates.

Several (14) commercially prepared, lyophilized Factor VIII concentrates were assayed for VIIIAHF, VIIIAg, and VIIIVWF. Significant levels of VIIIAg (immunologic) and VIIIVWF (von Willebrand Factor) were present in addition to VIIIAHF (Functional VIII, Antihemophilic Factor, Factor VIII coagulant activity). An average of 0.95 units of VIIIVWF (range 0.47--1.7) were present for every 1.0 unit of VIIIAHF (as stated on the manufacturer's label). We suggest that the various lyophilized preparations of Factor VIII concentrate available could be assayed for VIIIVWF and should be tested therapeutically in patients with von Willebrand disease.