title: A collaborative study to establish a Korean Standard for factor VIII:C concentrate.
abstract: OBJECTIVE
  A collaborative study among five laboratories including three manufacturers and two national control laboratories was carried out to evaluate the suitability of a candidate to serve as a Korean Standard for factor VIII:C concentrate.
  
  
  METHODS
  Two approaches were attempted to determine the potency of this candidate. The one is a one-stage clotting assay and the other is a chromogenic assay. To achieve acceptable precision and accuracy, the following recommendations by the International Society on Thrombosis and Haemostasis were adopted in the assays, e.g., pre-dilution of samples in factor VIII (FVIII)-deficient plasma, inclusion of 1% albumin in the dilution buffer and calibration against the sixth International Standard for the blood coagulation factor VIII:C concentrate, coded 97/616.
  
  
  RESULTS
  The data collected within each laboratory and among laboratories for both assays employed here were in good agreements in the calibration of the candidate preparation against the International Standard. The overall potencies by the one-stage clotting assay and the chromogenic assay, however, showed recognizable differences between them. Each differed from each other in that the potency obtained from chromogenic assay was approximately 17% lower than that from one-stage clotting assay. The estimated geometric mean value obtained from the one-stage clotting assay was 8.4 international units (IU)/vial and that from the chromogenic assay was 6.7 IU/vial.
  
  
  CONCLUSIONS
  Based on the results of this collaborative study, the candidate standard is judged to be suitable to serve as a Korean National Standard for factor VIII:C concentrate.
authors.affiliation: Biologics Evaluation Department, Korea Food and Drug Administration, 5 Nokbun-Dong, Eunpyung-Gu, Seoul, South Korea 122-704. hyena52000@yahoo.com
authors.forename: Hye Na
authors.initials: HN
authors.lastname: Kang
authors.forename: Soon Nam
authors.initials: SN
authors.lastname: Kim
authors.forename: Seok Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Seung Hwa
authors.initials: SH
authors.lastname: Hong
mesh_terms: D001681:Biological Assay / Q000379:methods; D001777:Blood Coagulation; D002863:Chromogenic Compounds; D004355:Drug Stability; D005169:Factor VIII / Q000592:standards*; D007723:Korea; D010446:Peptide Fragments / Q000592:standards; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012015:Reference Standards; D013696:Temperature
chemical_list: D002863:Chromogenic Compounds; D010446:Peptide Fragments; D011994:Recombinant Proteins; D005169:Factor VIII