Activity and Content of Factor VIII (FVIII) in Human Plasma: The Assessment of a Novel Immunoassay

Pharmacokinetic (PK) Analysis of a Novel Immunoassay in Hemophilia A

A novel immuno-assay is being evaluated for the measurement of Factor VIII. Current procedure measures a rate assay which is subject to much artefact. The hypothesis is that the new assay will give a reading of absolute quantities of FVIII which will provide a more suitable indicator of FVIII content for clotting factor manufacturers, physicians and patients.

Remnant samples collected in a clinical laboratory are assayed with the new procedure and compared with the standard functional activated partial thromboplastin time (APTT) assay. A PK study in seven study subjects with hemophilia A is being carried out using five different commercially licensed factor VIII concentrates and the blood samples drawn for the PK analysis are being measured for FVIII with the novel assay and compared with the standard APTT assay. The concentrates used in the PK studies are also being applied to the two assay systems to determine each product's specific activity.

Inclusion Criteria:

• adults with hemophilia A
• factor VIII less that 2%
• informed consent signed
• absence of an inhibitor

Exclusion Criteria:

• history of a high responding inhibitor anemia