American Board of Internal Medicine (ABIM) Certification Practice Exam

Which cholinesterase inhibitor is considered a first-line treatment for stable Myasthenia Gravis patients?

1. Pyridostigmine

2. Donepezil

3. Amytryptiline

4. Rivastigmine

The correct answer is: Pyridostigmine

Pyridostigmine is recognized as the first-line treatment for patients with stable Myasthenia Gravis due to its ability to increase the levels of acetylcholine at the neuromuscular junction. By inhibiting acetylcholinesterase, pyridostigmine prevents the breakdown of acetylcholine, thereby improving communication between nerve and muscle, which is crucial for muscle contraction. This is particularly important in Myasthenia Gravis, a condition where the body’s immune system attacks acetylcholine receptors, leading to muscle weakness. Other medications listed do not primarily target Myasthenia Gravis symptoms. Donepezil and rivastigmine are cholinesterase inhibitors typically used in the treatment of Alzheimer's disease, not Myasthenia Gravis. Meanwhile, amitriptyline is an antidepressant and not relevant to the management of this neuromuscular disorder. Thus, pyridostigmine stands out due to its specific action on neuromuscular transmission in the context of Myasthenia Gravis.