Sleep Pharmacotherapy: Principles & BZDs - Setting Sleep Stages
- Principles:
- Use lowest effective dose for shortest duration.
- Address underlying cause of insomnia.
- Taper gradually to prevent withdrawal.
- Caution: Elderly, pregnancy, substance abuse Hx.
- Benzodiazepines (BZDs):
- Mechanism: Potentiate GABA-A receptor → ↑ Cl⁻ channel opening frequency.
- Sleep Stages: ↓ sleep latency, ↓ N3 (slow-wave), ↓ REM; ↑ Stage 2, ↑ total sleep time.
- Adverse Effects: Sedation, dependence, withdrawal, cognitive impairment, respiratory depression.
- BZD Examples:
Class Drug t½ (hrs) Primary Use(s) Key ADRs Short-acting Triazolam 2-5 Sleep-onset insomnia Rebound insomnia, amnesia Intermediate Lorazepam 10-20 Insomnia, anxiety Sedation, dependence Long-acting Diazepam 20-100 Anxiety, muscle spasm Prolonged sedation, falls
⭐ Flumazenil is the specific antidote for benzodiazepine overdose.
Sleep Pharmacotherapy: Non-BZDs & Melatonin Agonists - Newer Sleep Promoters
Z-Drugs (Non-BZDs): Selective GABA-A (ω1) agonists. Fewer BZD-like effects (anxiolytic, anticonvulsant).
| Drug | Onset | Duration | Uses | Key SEs |
|---|---|---|---|---|
| Zolpidem | Rapid (~30m) | Short (IR/CR) | Onset/Maintenance Insomnia | Drowsiness, dizziness, CSRBs |
| Zaleplon | V. Rapid | V. Short | Onset, Mid-night (≥4h sleep) | Dizziness, headache; ↓next-day sedation |
| Eszopiclone | Rapid | Intermediate | Onset/Maintenance; Long-term | Unpleasant taste, somnolence |
Melatonin Agonists:
- Ramelteon:
- Selective MT1/MT2 agonist.
- Uses: Sleep-onset insomnia; no abuse potential.
- SEs: Dizziness, somnolence.
- Tasimelteon:
- MT1/MT2 agonist.
- Uses: Non-24 SWD (blind).
- SEs: Headache, ↑ALT.
Sleep Pharmacotherapy: Orexin Antagonists & Antidepressants - Alternative Sleep Routes
-
Orexin Receptor Antagonists (ORAs)
- Mechanism: Block wakefulness-promoting orexin A & B peptides in hypothalamus.
- Examples: Suvorexant, Lemborexant (DORAs - Dual Orexin Receptor Antagonists).
- Use: Insomnia (sleep onset & maintenance).
⭐ Suvorexant is a dual orexin receptor antagonist (DORA) that promotes sleep by blocking wakefulness-promoting orexin signals.
-
Sedating Antidepressants (Low-Dose)
- Doxepin: Tricyclic antidepressant (TCA); 3-6 mg for sleep maintenance (potent H1 blockade).
- Trazodone: Serotonin antagonist & reuptake inhibitor (SARI); 25-100 mg for insomnia, often with depression.
- Mirtazapine: Noradrenergic & specific serotonergic antidepressant (NaSSA); 7.5-15 mg for insomnia, especially with weight loss or anxiety (H1 blockade).
Sleep Pharmacotherapy: Narcolepsy, RLS, RBD - Beyond Insomnia Rx
Narcolepsy Management
| Drug | MOA (Simplified) | Primary Use | Key Adverse Effects |
|---|---|---|---|
| Modafinil | ↑DA, NE; ↓GABA | EDS | Headache, nausea, anxiety |
| Armodafinil | R-enantiomer of modafinil | EDS | Similar to modafinil, longer $t_{1/2}$ |
| Methylphenidate | CNS stimulant (DA/NE reuptake block) | EDS (2nd line) | Insomnia, irritability, abuse potential |
| Sodium Oxybate | GABA-B agonist | Cataplexy, EDS | Nausea, dizziness, resp. depression, abuse |
| %%{init: {'flowchart': {'htmlLabels': true}}}%% | |||
| flowchart TD |
Narco["💤 Narcolepsy
• Sleep disorder• Low orexin level"]
EDS["🥱 Daytime Sleep
• Excessive EDS• Primary symptom"]
Cata["⚡ Cataplexy
• Muscle weakness• Triggered emotion"]
Mod["💊 Wake Agents
• Modafinil drug• Methylphenidate"]
Oxy["💊 Sodium Oxybate
• Improves sleep• Reduces attacks"]
AntiD["💊 Antidepressant
• SSRI and SNRI• TCAs included"]
Narco --> EDS Narco --> Cata EDS --> Mod Cata --> Oxy Cata --> AntiD
style Narco fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8 style EDS fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C style Cata fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C style Mod fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style Oxy fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style AntiD fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
> ⭐ Sodium oxybate is highly effective for cataplexy in narcolepsy and has a significant abuse potential (GHB).
**Restless Legs Syndrome (RLS)**
* Dopamine Agonists (Pramipexole, Ropinirole): 1st line. AE: Augmentation, nausea.
* Alpha-2-delta ligands (Gabapentin, Pregabalin): For RLS with pain/insomnia. AE: Sedation.
**REM Sleep Behavior Disorder (RBD)**
* Clonazepam: 1st line. AE: Sedation, falls in elderly.
* Melatonin: Alternative, safer profile for long-term use.
> ## High‑Yield Points - ⚡ Biggest Takeaways
>
> * **Benzodiazepines & Z-drugs** (e.g., Zolpidem) act on **GABA-A receptors**; risk **tolerance, dependence, withdrawal**.
> * **Ramelteon**, a **melatonin (MT1/MT2) agonist**, is non-addictive, for **sleep-onset insomnia**.
> * **Suvorexant**, an **orexin antagonist**, aids **sleep onset & maintenance**.
> * Low-dose **Doxepin** (TCA) targets **H1 receptors** for **sleep maintenance insomnia**.
> * **Trazodone** is often used off-label for insomnia, especially with **depression**.
> * Avoid **BZDs** in **elderly** (↑ fall risk) and **obstructive sleep apnea**.