title: Role for standards in assays of botulinum toxins: international collaborative study of three preparations of botulinum type A toxin.
abstract: The biological activity of therapeutic preparations of botulinum type A toxin is currently expressed in units defined on the basis of the median lethal intraperitoneal dose of that preparation in mice at 72 h, the LD50 dose. In this study we describe the comparison, by ten laboratories in five countries, of three different formulations of botulinum type A toxin using the mouse lethality test, and also using the relative activities of the preparations. The results of this study show that use of a standard preparation and expression of relative potency gives substantially greater consistency between and within laboratories than when mouse LD50 unit is used to define activity of botulinum toxin.
authors: Division of Bacteriology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire, EN6 3QG, UK. dsesardic@nibsc.ac.uk
authors: Dorothea
authors: D
authors: Sesardic
authors: Tong
authors: T
authors: Leung
authors: Rose
authors: R
authors: Gaines Das
mesh_terms: D000818:Animals; D001681:Biological Assay; D001688:Biological Products / Q000032:analysis / Q000302:isolation & purification / Q000592:standards / Q000633:toxicity; D019274:Botulinum Toxins, Type A / Q000032:analysis / Q000302:isolation & purification / Q000592:standards* / Q000633:toxicity; D003299:Cooperative Behavior; D007928:Lethal Dose 50; D051379:Mice; D012015:Reference Standards
chemical_list: D001688:Biological Products; D019274:Botulinum Toxins, Type A