Pharmacotherapy for Substance Use Disorders

Opioid Use Disorder Rx - Taming the Dragon

• MAT is cornerstone for OUD. 📌 MAT: Methadone, Buprenorphine, Naltrexone ("My Best New-life").

Start["🩺 OUD Diagnosis
• Opioid use disorder• Clinical assessment"]

Withdrawal["❓ Acute Withdrawal?
• Assess symptoms• COWS score check"]

Manage["⚠️ Manage Withdrawal
• Symptomatic Rx• Buprenorphine start"]

MAT["📋 Select MAT
• Pick therapy type• Patient preference"]

Methadone["💊 Methadone
• Full mu-agonist• Highly regulated"]

Buprenorphine["💊 Buprenorphine
• Partial agonist• Ceiling effect"]

Naltrexone["💊 Naltrexone
• Mu-antagonist• Opioid-free 7-10d"]

Start --> Withdrawal Withdrawal -->|Yes| Manage Withdrawal -->|No/Stabilized| MAT Manage --> MAT MAT --> Methadone MAT --> Buprenorphine MAT --> Naltrexone

style Start fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8 style Withdrawal fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E style Manage fill:#FDF4F3, stroke:#FCE6E4, stroke-width:1.5px, rx:12, ry:12, color:#B91C1C style MAT fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E style Methadone fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style Buprenorphine fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534 style Naltrexone fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534

> ⭐ Buprenorphine, a partial μ-opioid agonist, has a ceiling effect on respiratory depression, making it safer in overdose than full agonists like methadone.


##  Alcohol Use Disorder Rx - Quenching the Fire

Pharmacotherapy manages withdrawal & prevents relapse.

**Withdrawal (CIWA-Ar Guided):**
```mermaid
%%{init: {'flowchart': {'htmlLabels': true}}}%%
flowchart TD
    AUD["<b>🍺 AUD Withdrawal</b><br><span style='display:block; text-align:left; color:#555'>• Alcohol cessation</span><span style='display:block; text-align:left; color:#555'>• Clinical onset</span>"]
    
    CIWA["<b>📋 CIWA-Ar Score</b><br><span style='display:block; text-align:left; color:#555'>• Assess severity</span><span style='display:block; text-align:left; color:#555'>• Clinical scale</span>"]
    
    Support["<b>✅ Supportive Care</b><br><span style='display:block; text-align:left; color:#555'>• Hydration therapy</span><span style='display:block; text-align:left; color:#555'>• Close monitoring</span>"]
    
    Benzo["<b>💊 Benzodiazepines</b><br><span style='display:block; text-align:left; color:#555'>• Lorazepam 2-4mg</span><span style='display:block; text-align:left; color:#555'>• Diazepam 5-10mg</span>"]
    
    Taper["<b>👁️ Taper Process</b><br><span style='display:block; text-align:left; color:#555'>• Follow CIWA-Ar</span><span style='display:block; text-align:left; color:#555'>• Slow reduction</span>"]

    AUD --> CIWA
    CIWA -->|Under 10| Support
    CIWA -->|Over 10| Benzo
    Benzo --> Taper

    style AUD fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8
    style CIWA fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
    style Support fill:#F6F5F5, stroke:#E7E6E6, stroke-width:1.5px, rx:12, ry:12, color:#525252
    style Benzo fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
    style Taper fill:#EEFAFF, stroke:#DAF3FF, stroke-width:1.5px, rx:12, ry:12, color:#0369A1

Relapse Prevention Agents:

Agent Selection:

⭐ Disulfiram inhibits aldehyde dehydrogenase, leading to acetaldehyde accumulation if alcohol is consumed.

Nicotine & Other SUDs Rx - Clearing the Smoke & Shadows

Pharmacotherapy for Nicotine Dependence:

Other SUDs:

• Benzodiazepine Withdrawal: Gradual taper (↓10-25% q 1-2 wks). Switch to long-acting BZD (e.g., diazepam). 📌 Taper Slow, Avoid the Woe.

High‑Yield Points - ⚡ Biggest Takeaways

• Naltrexone (oral/injectable) for opioid & alcohol dependence; CI: acute hepatitis, current opioid use (precipitates withdrawal).
• Disulfiram for alcohol deterrence via acetaldehyde syndrome; monitor LFTs, ensure abstinence before starting.
• Acamprosate for alcohol relapse prevention (GABA/glutamate modulation); renally excreted, safe with liver disease.
• Methadone for opioid maintenance therapy (OMT); risk of QTc prolongation, numerous drug interactions, supervised dispensing.
• Buprenorphine (± naloxone) for OMT; safer in overdose than methadone due to ceiling effect on respiratory depression.
• Varenicline for smoking cessation; highest efficacy, monitor for neuropsychiatric effects and cardiovascular events (rare).