How do anti toxins work?
Addiction module
The antitoxin is generally less stable than the toxin due to its degradation by proteases already present in the cell. For example, in the ccdAB proteic addiction module, the "Lon" protease  degrades the antitoxin, but also serves many unrelated proteolytic roles, such as degrading oxidated mitochondrial products. This may indicate that the development of these addiction molecules "co-opted" existing cell utilities.
The antitoxin in proteic addiction modules functions by binding directly to the toxin and preventing its mode of action. Once the antitoxin has bound to the toxin, the toxin prevents the proteases normally responsible for degrading antitoxin to do so, maintaining the neutralization of that individual toxin molecule.
Defensin
The mammalian defensins (Table below) are different from arthropod defensins. The latter are more similar to protein scorpion toxins. Subsequent investigations confirmed relationships between scorpion toxins that block potassium channels and insect defensins in their three-dimensional structure and their disruption of membrane functions of invasive microbes. Experimental deletion of a small loop of a defensin molecule from a Hymenopteran parasitoid venom that shares attributes of scorpion toxin, removed steric hindrance of interactions between peptides and channels. The resulting peptide was neurotoxin that selectively inhibited potassium channels, binding to the channels in the same manner as scorpion toxins. The results presented structural and functional evidence for the basis of toxin evolution.