Which statement about edrophonium is true?

Which statement about edrophonium is true?

• A. Used to diagnose myasthenia gravis due to very fast onset
• B. Used to reverse nondepolarizing blockade but has long duration
• C. Cannot cross the blood-brain barrier
• D. Is a beta-blocker

Answer: (A)

Edrophonium is a short-acting acetylcholinesterase inhibitor used in the Tensilon test to diagnose myasthenia gravis. Its effect is rapid and brief, so acetylcholine at the neuromuscular junction increases quickly and a patient with MG shows a prompt, temporary improvement in strength within seconds to a minute after administration. This very fast onset makes it the best statement about edrophonium in this context, since it directly reflects its diagnostic use. The idea that it reverses nondepolarizing blockade with a long duration is incorrect because its action wears off within minutes, not hours. It does not cross the blood-brain barrier due to its quaternary ammonium structure, and it is not a beta-blocker.

Edrophonium is a short-acting acetylcholinesterase inhibitor used in the Tensilon test to diagnose myasthenia gravis. Its effect is rapid and brief, so acetylcholine at the neuromuscular junction increases quickly and a patient with MG shows a prompt, temporary improvement in strength within seconds to a minute after administration. This very fast onset makes it the best statement about edrophonium in this context, since it directly reflects its diagnostic use.

The idea that it reverses nondepolarizing blockade with a long duration is incorrect because its action wears off within minutes, not hours. It does not cross the blood-brain barrier due to its quaternary ammonium structure, and it is not a beta-blocker.