What cholinergic agent is used in the treatment of myasthenic crises?

Pyridostigmine is the correct choice because it is a reversible acetylcholinesterase inhibitor that increases the availability of acetylcholine at the neuromuscular junction. In patients with myasthenia gravis, a disorder characterized by weakness and rapid fatigue of the voluntary muscles, the effectiveness of neuromuscular transmission is compromised due to the presence of antibodies that block or destroy nicotinic acetylcholine receptors. By inhibiting the enzyme that breaks down acetylcholine, pyridostigmine enhances communication between nerves and muscles, thereby improving muscle strength and alleviating symptoms during a myasthenic crisis.

Other options do not serve this function. Atropine is an anticholinergic agent that blocks acetylcholine receptors and is used to reduce secretions and treat bradycardia, but it would worsen the symptoms of myasthenia gravis. Donepezil and galantamine are also acetylcholinesterase inhibitors, but they are primarily used in the management of Alzheimer's disease and do not have the same clinical application in treating myasthenic crises as pyridostigmine does. Thus, pyridostigmine’s role in enhancing neuromuscular transmission specifically addresses the urgent