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PRINCIPLES OF IN VIVO RECOVERY AND SURVIVAL STUDIES
Author(s) -
Allain JeanPierre
Publication year - 1984
Publication title -
scandinavian journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0036-553X
DOI - 10.1111/j.1600-0609.1984.tb02773.x
Subject(s) - in vivo , body weight , titer , medicine , chemistry , immunology , biology , microbiology and biotechnology , antibody
ABSTRACT: The great variety of Factor VIII preparations available to the clinician to treat hemophilia A patients requires a careful study of both in vivo recovery and survival of VIII:C. These studies are valid only if strict rules are followed. Severe hemophilia A patients without inhibitor, non bleeding or bleeding in small capacity joints and not treated for at least five days are selected. The dose of infused VIII:C can be calculated either from the labeled value or from local measurement using a concentrate calibrated against the WHO standard as reference. At least 20 IU/kg of body weight of VIII:C are infused. Plasma samples collected before, 15, 30 and 60 minutes post‐infusion allow to identify the peak of VIII:C plasma level from which in vivo recovery is calculated. Samples collected 4, 8–12, 24 and 36–48 h post‐infusion allow to evaluate VIII:C half‐life on the basis of VIII:C plasma level of 4 of these samples. Both one‐ and two‐stage Factor VIII assay are equally acceptable provided a proper reference calibrated against the WHO plasma standard is used. In vivo recovery is expressed in percent of a theoretical value obtained by various means. Several mathematical formulae are available to calculate the VIII:C biological half‐life. These in vivo studies are not only useful to evaluate therapeutic preparations but also to detect low titer inhibitors.