Learning Objectives
By the end of this session, the learner will be able to distinguish between GABAergic and Non-GABAergic sedative-hypnotics, including their molecular mechanisms, unique clinical applications for sleep and anxiety, and the specific role of receptor subtypes (
1. The “Z-Drugs”: Selective Hypnotics
These are non-benzodiazepine drugs that act on the BZ site of the 
| Drug Class | Mechanism | Clinical Advantages |
|---|---|---|
| Zolpidem, Zaleplon, Eszopiclone | Selective receptor agonists. |
Maintains sleep architecture with less cognitive impairment or “hangover” than BZs. |
Antidote: Toxicity/overdose is reversed by Flumazenil.Key Side Effect: Unusual sleep behaviors (e.g., sleep-eating or sleep-driving).
2. Buspirone: The Non-Sedative Anxiolytic
Buspirone is the “odd one out”—it treats anxiety without touching the GABA system at all.
| Feature | Details |
|---|---|
| Mechanism |  partial agonist (Serotonin). |
| Clinical Use | Generalized Anxiety Disorder (GAD). |
| Onset | Slow (takes 1–2 weeks to be effective). |
| Major Benefit | No sedation, no addiction risk, and no interaction with alcohol. |
3. Orexin and Melatonin Modulators
These drugs target the “On/Off” switches of wakefulness rather than providing global CNS depression.
| Drug Category | Mechanism | Clinical Use |
|---|---|---|
| Suvorexant | Orexin receptor antagonist (blocks the “wake” signal). | Insomnia helps patients stay asleep. |
| Ramelteon | Melatonin receptor agonist ( ). |
Insomnia regulates the circadian rhythm. |
Clinical Pearls:
- The Alcohol Rule: While BZs and Z-drugs interact dangerously with alcohol, Buspirone and Ramelteon do not, making them safer for patients with a history of substance use.
- BZ2 vs BZ1: Remember that
- Orexin Antagonists: Suvorexant is contraindicated in patients with Narcolepsy (since narcoleptics already lack orexin).