Safety Study of 7 Botulinum Antitoxin Serotypes Derived From Horses

Clostridial toxins are amongst the most toxic substances known to science (Middlebrook, 1995). In the United States and other countries, human exposure to Clostridium botulinum toxins usually occurs through food poisoning, wound botulism and colonizing infections in neonates. Recent events have heightened concern about the possibility of botulinum toxins being used in a bioterrorist attack. In order to be prepared for a biological attack as well as the usual human exposures, numerous therapeutic products have been or currently are undergoing development to treat or prevent botulism, including the use of human or equine derived antibodies for post-exposure prophylaxis of botulinum toxin exposure (Gelzleichter et al, 1999; Hibbs et al, 1996; Metzger and Lewis, 1979 and Keller and Stiehm, 2000). Botulinum antitoxins have been in use to treat adult exposure to botulinum toxin for at least 40 years (Cupo et al, 2001). The use of botulinum antitoxins to treat individuals exposed to botulinum toxin is similar to the use of passive immune therapy with immune globulins collected from immunized or convalescing human donors to treat a wide range of bacterial and viral infectious diseases (Chippaux et al, 1998). NP-018 (heptavalent equine-derived botulinum antitoxin) is prepared from plasma obtained from horses that have been immunized with a specific subtype of botulinum toxoid and toxin. Each individual horse is immunized against a single botulinum toxin subtype. Plasma is pooled from horses that have been immunized with the same botulinum toxin subtype. For each antitoxin serotype (A-G), a despeciated product will be produced by pepsin digestion of the IgG monomer in the equine plasma, yielding predominantly F(ab¢)2 fragment. Following the formulation, the seven antitoxin serotypes will be blended into a heptavalent product and filled into single-use vials. The present clinical study is intended to assess the pharmacokinetics and safety of NP 018 following intravenous administration. The pharmacokinetics of NP 018 will be comparable to other equine derived antitoxin products. NP 018 will be safe to administer to normal healthy volunteers.