Establishment of the human coagulation factor VII concentrate European Pharmacopoeia biological reference preparation batch 1.

For the potency assay of human coagulation factor VII concentrate preparations according to the European Pharmacopoeia (Ph. Eur.) a reference preparation calibrated in International Units (IU) is needed. Currently, the 1st International Standard (97/592, potency: 6.3 IU/ampoule) but no Ph. Eur. reference preparation is available. A collaborative study was run to calibrate a candidate Ph. Eur. Biological Reference Preparation (BRP) for human coagulation factor VII concentrate against the 1st International Standard; the BRP is intended to be used as working standard. A candidate BRP batch 1 was produced from a plasma-derived human factor VII concentrate preparation available on the European market. It fulfilled the requirements of a BRP with regard to precision and homogeneity of fill, residual water content and stability. In addition, the content of activated factor VII was low. Sixteen laboratories from 9 countries participated in the collaborative study. The potency of the candidate BRP was determined using the participants' chromogenic assay based on the Ph. Eur. and their in-house clotting assay, if available. The statistical model used for analysis of the results from most laboratories was the maximum likelihood of the parallel line model following a logarithmic transformation of the responses. In the chromogenic assay, a potency estimate of 8.2 IU/vial (+/-3.7%) was obtained for the candidate BRP. Results from the clotting assay were lower and less homogenous (6.7 IU/vial+/-11.6%). The results from the collaborative study showed that the candidate BRP is suitable as a reference standard for the chromogenic assay according to the Ph. Eur. It was adopted by the Ph. Eur. Commission in March 2006 as official Ph. Eur. BRP for this purpose.