Which statement best describes the mechanism by which neostigmine produces its therapeutic effect in myasthenia gravis?

• A It directly activates nicotinic receptors at the neuromuscular junction
• B It inhibits acetylcholinesterase reversibly, increasing synaptic acetylcholine levels ✓
• C It stimulates choline acetyltransferase to synthesize more acetylcholine
• D It blocks the presynaptic reuptake of acetylcholine into nerve terminals

Explanation

Neostigmine is a reversible inhibitor of acetylcholinesterase (AChE); it forms a carbamylated enzyme–AChE complex that persists for minutes to hours. By preventing ACh hydrolysis, it increases the concentration and duration of ACh in the synaptic cleft, compensating for the reduced number of functional nicotinic receptors in myasthenia gravis. It does not directly stimulate receptors or affect synthesis.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.