Why is Botulinum toxin the most potent poison known?

Question

Botulinum toxin (trade name Botox) inhibits acetylcholine release in neurons and causes botulism, an acute paralytic disease which leads to nerve degeneration and takes a long time to recover. I've read the statement that Botox is the most potent poison we know a few times now and was wondering *why exactly* it is. All sources I've found only claim *that* it is, without explanation.

Answer 1

Potency is determined by the LD50 in the case of toxic substances. So, the only reason that botulinum toxin is more potent than, say, batrachotoxin, is because it takes less (a lower dose) of botulinum toxin to kill 50% of the subjects. Ultimately, this may have to do with affinity for receptors, biodegradation (metabolism), distribution, biologic half-life, and many other factors.