Pyridostigmine improves muscle strength by which mechanism?

• A. Inhibiting acetylcholine release
• B. Blocking acetylcholine receptors
• C. Preventing breakdown of acetylcholine
• D. Inhibiting dopamine reuptake

Answer: (C)

Pyridostigmine works by inhibiting acetylcholinesterase, the enzyme that breaks down acetylcholine in the neuromuscular junction. By blocking this enzyme, acetylcholine remains in the synaptic cleft longer and at higher concentrations, leading to more acetylcholine binding to nicotinic receptors on the muscle endplate. This increases the end-plate potential and strengthens muscle contraction, which is particularly helpful in myasthenia gravis where fewer receptors are available. It does not reduce acetylcholine release, block acetylcholine receptors, or affect dopamine reuptake, making this mechanism the correct way it improves muscle strength.