Validation of a procedure for potency assessing of a high purity factor VIII concentrate--comparison of different factor VIII coagulant assays and effect of prediluent.
The assessment of factor VIII coagulant activity (FVIII:C) in recently available highly purified and concentrated FVIII therapeutic products calls for careful evaluation of assay methodologies. We assayed more than 130 batches of a concentrate with a specific activity of about 150 FVIII:C units/mg protein, using one-stage and two-stage clotting and chromogenic methods. There was good agreement between the potency estimates obtained with the different methods. We also compared the FVIII:C potencies obtained after predilution in buffer or FVIII-deficient plasma using either calibrated plasma or FVIII concentrate as references. With the one-stage assay we found a marked discrepancy between the potency values obtained with buffer and with FVII-deficient plasma used as prediluents. In order to validate our "in vitro" data we performed 6 "in vivo" analyses in severe haemophilia A patients. On the basis of the overall data obtained we chose to label FVIII potency by using FVIII-deficient plasma as prediluent, reference plasma as standard and the chromogenic assay method.
Mazurier
C
C
Centre Régional de Transfusion Sanguine, Lille, France.
Parquet-Gernez
A
A
Goudemand
M
M
D001780:Blood Coagulation Tests / Q000379:methods* / Q000592:standards; D002021:Buffers; D002863:Chromogenic Compounds; D005069:Evaluation Studies as Topic; D005169:Factor VIII / Q000032:analysis* / Q000592:standards / Q000627:therapeutic use; D006467:Hemophilia A / Q000097:blood / Q000188:drug therapy; D006801:Humans; D010949:Plasma; D012015:Reference Standards
D002021:Buffers; D002863:Chromogenic Compounds; D005169:Factor VIII