A short-acting cholinesterase inhibitor was historically used as an intravenous diagnostic test in a patient presenting with fluctuating ptosis and fatigable weakness of limb muscles. The drug produces clear improvement within seconds to minutes. Which agent fits this description?

• A Pyridostigmine
• B Rivastigmine
• C Donepezil
• D Edrophonium ✓

Explanation

Edrophonium binds acetylcholinesterase briefly and reversibly through electrostatic attraction, producing improvement within 30 to 60 seconds lasting about 5 minutes, making it ideal for the Tensilon test. Pyridostigmine acts for 3 to 6 hours and is used for treatment, not diagnosis. Rivastigmine and donepezil are centrally acting agents developed for Alzheimer disease, not for neuromuscular testing.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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