Which subunit composition of the GABA-A receptor explains why zolpidem produces hypnosis with relatively little muscle relaxation or anxiolysis compared to classical benzodiazepines?

• A Antagonism at the gamma-2 subunit
• B Equal affinity for all alpha subunit isoforms
• C Selective agonism at the alpha-2 subunit only
• D High affinity for receptors containing the alpha-1 (BZ1) subunit ✓

Explanation

The classical benzodiazepines bind alpha-1, alpha-2, alpha-3 and alpha-5 containing GABA-D receptors equally. Sedation is largely mediated by alpha-1 receptors, while anxiolysis and muscle relaxation depend mainly on alpha-2. Zolpidem binds selectively to alpha-1 containing receptors, giving strong hypnotic activity with comparatively little muscle relaxant or anxiolytic effect and a lower dependence profile. This selectivity defines the Z-drugs.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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