Question

Drug to differentiate Myasthenia gravis from cholinergic crisis?

• A. Pyridostgmine
• B. Edrophonium
• C. Methacholine
• D. Clonidine

Answer 1

The Correct Option is B

To differentiate Myasthenia gravis from a cholinergic crisis, the drug used is Edrophonium. This is known as the Edrophonium test or Tensilon test. Myasthenia gravis is an autoimmune disorder characterized by muscle weakness that worsens with activity. It is caused by autoantibodies that attack the acetylcholine receptors at the neuromuscular junction. In a cholinergic crisis, however, there is an excess of acetylcholine often due to overdose of anticholinesterase medications that can mimic or exacerbate symptoms of muscle weakness.

When Edrophonium, a short-acting anticholinesterase agent, is administered, it temporarily increases the availability of acetylcholine at the neuromuscular junction. The test results are as follows:

• If symptoms improve, it indicates that the patient is indeed experiencing myasthenia gravis due to insufficient acetylcholine action.
• If symptoms worsen or there is no improvement, it suggests a cholinergic crisis where there is already an excess of acetylcholine.

It's important to perform this test under controlled conditions as it may cause dangerous side effects. The correct answer here is Edrophonium because it uniquely aids in distinguishing myasthenic crisis from cholinergic crisis by evaluating the patient's response.