Discrepancies in potency assessment of recombinant FVIII concentrates.
Results of assays of recombinant FVIII concentrates have been reviewed over a 10-year period. Initially there was wide variability between laboratories but this was minimised by the development of standardised assay methodology, in particular the use of haemophilic plasma for pre-dilution and 1% albumin in assay buffers. Using this standardised methodology and concentrate standards, there were no major differences in potency between one-stage, two-stage and chromogenic assays on the two full-length recombinant FVIII concentrates. However, using a plasma standard, the chromogenic method gave much higher potencies than the one-stage method on the same concentrates, and this explains a similar discrepancy found in patients' post-infusion samples after injection of recombinant concentrates. It is suggested that concentrate standards be used for such post-infusion samples in order to minimise this discrepancy.
Barrowcliffe
T W
TW
NIBSC, Potters Bar, UK.
Raut
S
S
Hubbard
A R
AR
D001681:Biological Assay; D001778:Blood Coagulation Disorders / Q000188:drug therapy*; D005169:Factor VIII / Q000592:standards* / Q000627:therapeutic use; D006801:Humans; D011994:Recombinant Proteins / Q000592:standards / Q000627:therapeutic use; D012015:Reference Standards; D014944:World Health Organization
D011994:Recombinant Proteins; D005169:Factor VIII