Question

Which one of the following is a reversible cholinesterase inhibitor ?

• A. Physostigmine
• B. Carbachol
• C. Bethanechol
• D. Malathion

Hint:

"Stigmines" (Physostigmine, Neostigmine) are typically reversible inhibitors.

Answer 1

The Correct Option is A

Step 1: Concept
Cholinesterase inhibitors prevent the breakdown of acetylcholine, increasing its concentration at the synapse.

Step 2: Meaning
Reversible inhibitors bind to the enzyme for a limited time, whereas irreversible ones (like organophosphates) bind permanently.

Step 3: Analysis
Carbachol and Bethanechol are direct-acting cholinergic agonists, not inhibitors. Malathion is an irreversible organophosphate inhibitor. Physostigmine is a tertiary amine that reversibly inhibits the enzyme.

Step 4: Conclusion
Physostigmine is the correct example of a reversible cholinesterase inhibitor.

Final Answer: (A)