Botulinum toxin blocks neuromuscular transmission by the following mechanism:
Ref:KD Tripathi pharmacology 7th edition (page.no: 99) Botulinum toxins A and B are highly potent exotoxins produced by Clostridium botulinum that is responsible for Botulism. These neurotoxic proteins cause long-lasting loss of cholinergic transmission by interacting with axonal protein involved in exocytic release of Ach and thereby closing the calcium channel in the pre synaptic membrane
Closure of Ca++ channels at presynaptic membrane
Closure of Na+ channels at the postsynaptic membrane
Opening of K+ channels at the presynaptic membrane
Opening of Cl- channels at the postsynaptic membrane
Autonomic nervous system