title: In vivo recovery and survival of monoclonal-antibody-purified factor VIII concentrates.
abstract: In response to reports of discrepant in vitro assays of high-purity concentrates, a double-blind crossover study of in vivo recovery and half-life of two brands of monoclonal-antibody-purified factor VIII concentrates (Monoclate and Hemofil-M) was performed in 23 patients with hemophilia A. In vivo recoveries were close to values predicted from the labelled unitage when plasma samples were assayed by a one-stage method. When a two-stage assay was used, lower recoveries were calculated and the recovery with Hemofil-M was slightly but significantly lower than that with Monoclate. The concentrates were re-assayed in vitro by the two-stage method. Monoclate (which is assayed by the manufacturer using a two-stage method) contained 97% of the labelled potency and Hemofil-M (which is assayed by the manufacturer using a one-stage method) contained 81% of the labelled potency. Differences in in vitro and in vivo assay methods contribute to disparities between expected and observed factor VIII recovery. Clearance of Hemofil-M was significantly faster than that of Monoclate, but volume of distribution at the steady state, mean residence time, and plasma half-disappearance times of the two concentrates were not significantly different.
authors.affiliation: Department of Medicine, University of Southern California, Los Angeles.
authors.forename: C K
authors.initials: CK
authors.lastname: Kasper
authors.forename: H C
authors.initials: HC
authors.lastname: Kim
authors.forename: E D
authors.initials: ED
authors.lastname: Gomperts
authors.forename: K J
authors.initials: KJ
authors.lastname: Smith
authors.forename: P M
authors.initials: PM
authors.lastname: Salzman
authors.forename: D
authors.initials: D
authors.lastname: Tipping
authors.forename: R
authors.initials: R
authors.lastname: Miller
authors.forename: R M
authors.initials: RM
authors.lastname: Montgomery
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal; D002648:Child; D004311:Double-Blind Method; D005169:Factor VIII / Q000302:isolation & purification / Q000493:pharmacokinetics*; D006207:Half-Life; D006467:Hemophilia A / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000911:Antibodies, Monoclonal; D005169:Factor VIII