Zolpidem produces hypnotic effects with comparatively little anxiolytic, myorelaxant, or anticonvulsant activity. The pharmacological basis for this selectivity is:

• A Full agonist action at melatonin MT1 receptors
• B Selective blockade of GABA-B receptors in the limbic system
• C Selective positive modulation of GABA-A receptors containing the alpha-1 subunit ✓
• D Preferential binding to the picrotoxin site of the chloride channel

Explanation

Zolpidem is a non-benzodiazepine hypnotic (Z-drug) acting at the benzodiazepine site but showing selectivity for receptors containing the alpha-1 subunit, which mediate sedation, while alpha-2 and alpha-3 containing receptors mediate anxiolysis and muscle relaxation. This subunit selectivity explains its cleaner side-effect profile. Melatonin agonists are ramelteon and agomelatine, so option A belongs to a different drug class entirely.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

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