Tetanus toxin
tetanospasmin
What it isZinc protease that cleaves VAMP/synaptobrevin and blocks glycine and GABA release from spinal inhibitory interneurons; the cause of tetanus.
Why this oneReaches the cord by retrograde axonal transport from the neuromuscular junction, which is why it acts centrally although it never crosses the blood-brain barrier.
What limits itNot a medicine: protection comes from the toxoid vaccine, and treatment is antitoxin, wound care, and control of spasms.
NO BOXED WARNINGS