A patient reports difficulty sleeping and is prescribed zolpidem. Which statement correctly differentiates zolpidem (a Z-drug) from classical benzodiazepines?
- A Zolpidem preferentially binds GABA-A receptors containing the α1 subunit, conferring mainly sedative-hypnotic effects with less anxiolytic and muscle-relaxant action ✓
- B Zolpidem is a full agonist at all GABA-A receptor subtypes, providing equal anxiolytic and sedative effects
- C Zolpidem acts via a benzodiazepine site but lacks any dependence potential
- D Zolpidem increases slow-wave sleep and REM sleep equally
Correct answer: A. Zolpidem preferentially binds GABA-A receptors containing the α1 subunit, conferring mainly sedative-hypnotic effects with less anxiolytic and muscle-relaxant action
Explanation
Z-drugs (zolpidem, zopiclone, zaleplon) are non-benzodiazepine GABA-A modulators that selectively bind receptors containing the α1 subunit, which mediates sedation, amnesia, and anticonvulsant effects. This relative selectivity spares α2/α3-containing receptors responsible for anxiolysis and muscle relaxation, giving zolpidem a predominantly hypnotic profile. However, at higher doses, selectivity is lost and dependence potential remains.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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