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.