Which medication class improves neuromuscular transmission in MG?

• A. Calcium channel blockers
• B. Beta blockers
• C. Acetylcholinesterase inhibitors
• D. Antibiotics

Answer: (C)

Myasthenia gravis impairs neuromuscular transmission because there are fewer functional acetylcholine receptors at the motor end plate. The signal from nerve to muscle relies on acetylcholine binding to those receptors to generate an end-plate potential strong enough to trigger a muscle contraction. Increasing the amount of acetylcholine available in the synaptic cleft makes it more likely that the remaining receptors are activated sufficiently, improving transmission.

Acetylcholinesterase inhibitors do exactly this: they block the enzyme that breaks down acetylcholine, so acetylcholine stays in the synapse longer and can activate receptors longer and more effectively. This directly boosts the signaling at the NMJ and tends to improve muscle strength in MG. That’s why they’re used as the primary symptomatic treatment, with common examples including pyridostigmine and neostigmine.

Other options don’t enhance NMJ transmission in MG. Blocking calcium channels would reduce calcium influx into the nerve terminal, which lowers acetylcholine release rather than increases it. Beta blockers don’t affect the neuromuscular junction in this way, and antibiotics aren’t used to improve transmission (in fact, some can worsen MG symptoms).