What is the mechanism of action of acetylcholinesterase inhibitors in reversing nondepolarizing neuromuscular blockers?

• A. Directly depolarize the neuromuscular junction
• B. Inhibits acetylcholinesterase to increase acetylcholine at the neuromuscular junction
• C. Block nicotinic receptors
• D. Induce muscle fiber destruction

Answer: (B)

Nondepolarizing neuromuscular blockers work by competing with acetylcholine for nicotinic receptors at the motor end plate, preventing transmission and causing paralysis. Acetylcholinesterase inhibitors reverse this by blocking the enzyme that breaks down acetylcholine, so acetylcholine accumulates in the synaptic cleft. The increased ACh concentration makes it more likely to outcompete the blocker for nicotinic receptor binding, restoring receptor activation, end-plate potentials, and muscle contraction. This effect relies on enhancing ACh availability rather than directly stimulating or destroying the junction, and it can be accompanied by muscarinic side effects if not managed appropriately.