A 55-year-old man with chronic insomnia is started on a new dual orexin receptor antagonist. Through which mechanism does this drug class promote sleep?
- A Enhancing GABA-A receptor chloride conductance
- B Blocking wake-promoting orexin neuropeptides at OX1R and OX2R receptors ✓
- C Agonizing melatonin MT1 and MT2 receptors in the suprachiasmatic nucleus
- D Inhibiting histamine H1 receptors in the tuberomammillary nucleus
Correct answer: B. Blocking wake-promoting orexin neuropeptides at OX1R and OX2R receptors
Explanation
Dual orexin receptor antagonists (suvorexant, lemborexant, daridorexant) block orexin A and B from binding to OX1R and OX2R receptors, thereby reducing wake drive. This is distinct from GABAergic hypnotics (zolpidem), melatonin agonists (ramelteon), or antihistamines (diphenhydramine).
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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