Zolpidem produces hypnotic effects with minimal anxiolytic, myorelaxant, or anticonvulsant activity compared to diazepam. This selectivity is explained by:

• A Selective antagonism at alpha-2 subunit containing receptors
• B Irreversible occupancy of the picrotoxin site on the chloride channel
• C Its preferential binding to GABA-A receptors containing the alpha-1 subunit ✓
• D Activation of metabotropic GABA-B receptors in the thalamus

Explanation

Zolpidem binds the benzodiazepine site but has high affinity mainly for GABA-C receptors containing the alpha-1 subunit, which mediates sedation. Classical benzodiazepines bind all alpha subunit-containing receptors, producing the additional anxiolytic (alpha-2), myorelaxant (alpha-2, alpha-3, alpha-5) and anticonvulsant effects. This subunit selectivity gives zolpidem near-pure hypnosis. It does not act at the picrotoxin site or at GABA-B receptors.

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

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