The hypnotic selectivity of zolpidem over classical benzodiazepines, meaning strong sedation with minimal anxiolytic, myorelaxant, and anticonvulsant effects, is explained by which molecular feature?

• A Selective positive allosteric modulation of GABA-A receptors containing the alpha-1 subunit ✓
• B Direct opening of neuronal chloride channels independent of GABA
• C Irreversible antagonism of alpha-2 subunit containing GABA-A receptors
• D Partial agonism at melatonin MT1 receptors

Explanation

Zolpidem binds preferentially to benzodiazepine sites on GABA-A receptors containing the alpha-1 subunit (the BZ1 subtype), which mediates sedation. Classical benzodiazepines act equally on alpha-1, alpha-2, alpha-3, and alpha-5 receptors, which accounts for their additional anxiolytic, muscle relaxant, and anticonvulsant actions. Melatonin receptor agonism describes ramelteon, a different hypnotic class entirely.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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