This is the first report of the large-scale experimentally production of an equine antivenom against redback spider (Latrodectus hasseltii) lived in Japan. We captured 10,000 redback spiders in Japan and prepared the toxoids of crude venom extract, mixed the toxoids with mineral oil adjuvant, and immunized repeatedly it to healthy horses over a period of several weeks. Then, we separated the horse plasma, and purified the γ-globulin fraction and stocked as a purified antivenom concentrate. Consequently, we manufactured approximately 6,500 vials of a single-dose freeze-dried test lot from a portion of the purified γ-globulin fraction, equivalent to the extract derived from 520 spiders. This test lot had an antitoxin titer comparable to that of a similar drug commercially available overseas (liquid preparation), and the other quality met all reference specifications pre-specified based on the Minimum Requirements for Biological Products and other guidelines relevant for existing antivenom drug products in Japan.
