FVIII Recovery after a Single Infusion of Recalibrated ReFacto in 14 Severe Hemophilia A Patients.

Background: A field study among 6 reference laboratories in the EU using chromogenic substrate assays revealed in some laboratories a FVIII level lower than expected when measuring the potency of ReFacto, a B-domain deleted recombinant FVIII concentrate. In an attempt to resolve these discrepancies, the standard used for establishing the potency of ReFacto was recalibrated in 2003. Indeed after this recalibration, the amount of ReFacto protein in each International Unit (IU) has increased by approximately 20 percent without change in the labeled dosage strength.