Opioid Use Disorder

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OUD Basics - The Poppy Problem

  • Definition: A problematic pattern of opioid use leading to clinically significant impairment or distress (DSM-5). ICD-11: Opioid Dependence. Key features: craving, tolerance, withdrawal.
  • Common Opioids:
    • Natural: Opium, Morphine, Codeine.
    • Semi-synthetic: Heroin (diacetylmorphine), Buprenorphine, Oxycodone.
    • Synthetic: Fentanyl, Methadone, Tramadol, Pethidine.
  • Routes of Administration: Oral, intranasal (snorting), intravenous (IV), inhalation (smoking, e.g., "chasing the dragon").
  • Indian Epidemiology (AIIMS, 2019): Approx. 2.8% of population (10-75 yrs) reported past-year opioid use; ~2.1% are users of concern. Heroin is the most common illicit opioid. Opium poppy seed pod with latex

⭐ Heroin (diacetylmorphine) is rapidly hydrolyzed to 6-monoacetylmorphine (6-MAM) and then to morphine in the body, both of which are active. This contributes to its potent and rapid effects.

Brain Hijack - How Opioids Work

Opioids bind to μ, κ, δ receptors, primarily Gi-coupled.

  • Receptor Functions:
    • μ (Mu): Euphoria, analgesia, respiratory depression, miosis, ↓GI motility. 📌 Key for analgesia & addiction.
    • κ (Kappa): Spinal analgesia, dysphoria, sedation, miosis.
    • δ (Delta): Analgesia, antidepressant/anxiolytic effects.
  • Cellular Mechanism:
    • ↓Adenylyl cyclase → ↓cAMP.
    • Postsynaptic: ↑K+ efflux → hyperpolarization.
    • Presynaptic: ↓Ca2+ influx → ↓neurotransmitter release.
  • Reward Pathway Activation:
    • VTA: μ-agonism inhibits GABAergic neurons.
    • → Disinhibition of VTA dopamine neurons.
    • → ↑Dopamine in Nucleus Accumbens (NAc) → euphoria & reinforcement.
  • Neuroadaptation:
    • Tolerance: ↓Receptor response → ↓drug effect.
    • Dependence: Physiological adaptation; withdrawal on cessation.

Opioid mechanism on neuron and reward pathway

⭐ The μ (mu) opioid receptor is primarily responsible for euphoria and respiratory depression.

Signs & Symptoms - Highs and Lows

Opioid Intoxication vs. Withdrawal

FeatureIntoxication ("High")Withdrawal ("Low")
Key TriadMiosis, Resp. Depression, Coma-
CNSEuphoria, drowsinessDysphoria, anxiety, insomnia, yawning
PupilsMiosis (pinpoint)Mydriasis (dilated)
GITConstipationN/V/D, cramps
Autonomic↓HR, ↓BP (severe)↑HR, ↑BP, sweating, piloerection, lacrimation, rhinorrhea, fever
Muscles-Myalgia, arthralgia
-   📌 Mnemonic: e.g., 'MY LEGS CRAMP' (Myalgia, Yawning, Lacrimation, Emesis, Gooseflesh, etc.)
-   COWS Scale (Severity): Mild **5-12**, Mod **13-24**, Mod Sev **25-36**, Sev **>36**.
  • ⭐ > Piloerection ("gooseflesh") during opioid withdrawal is the origin of the term "cold turkey".

Flowchart: Opioid Withdrawal Timeline

Diagnostic Criteria (DSM-5/ICD-11)

  • Problematic opioid use → impairment/distress. ≥2 criteria/12mo (e.g., tolerance, withdrawal, craving, loss of control).

Treatment Toolkit - Road to Recovery

  • Pharmacological Management

    • Detoxification:

      • Clonidine, lofexidine for autonomic symptoms.
      • Gradual opioid agonist taper (e.g., methadone, buprenorphine).
    • Maintenance Therapy:

      DrugMOAKey Pro(s)Key Con(s)Critical Dosing/Timing
      MethadoneFull $\mu$-agonistEffective, ↓cravingQTc risk, OD riskStart 20-30mg, supervised
      BuprenorphinePartial $\mu$-agonist; $\kappa$-antagonistCeiling effect (safer), ↓stigma, sublingualPrecipitated withdrawalStart COWS ≥8-12; often +Naloxone
      Naltrexone$\mu$-antagonistNon-addictive, oral/IMNeeds full detox, hepatotoxicityOpioid-free 7-10 days
  • Non-Pharmacological Interventions: Key psychosocial interventions include:

    • Cognitive Behavioral Therapy (CBT)
    • Motivational Interviewing (MI)
    • Contingency Management (CM)
    • Support groups (e.g., Narcotics Anonymous - NA)
  • Harm Reduction Strategies: Strategies to minimize negative consequences:

    • Needle and syringe programs (NSPs)
    • Distribution of naloxone kits for overdose reversal

⭐ Buprenorphine's ceiling effect on respiratory depression makes it safer in overdose than full agonists like methadone.

High‑Yield Points - ⚡ Biggest Takeaways

  • Opioid intoxication triad: pinpoint pupils (miosis), respiratory depression, altered mental status/coma.
  • Naloxone is the life-saving antidote for acute overdose, rapidly reversing respiratory depression.
  • Opioid withdrawal: severe flu-like symptoms (lacrimation, rhinorrhea, mydriasis, piloerection, muscle aches); not typically life-threatening.
  • Methadone (long-acting agonist) and buprenorphine (partial agonist) are crucial for Opioid Substitution Therapy (OST/MAT).
  • Naltrexone (antagonist) aids relapse prevention in detoxified individuals.
  • Clonidine alleviates autonomic hyperactivity during withdrawal.
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Practice Questions: Opioid Use Disorder

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A patient presents to the emergency department with vomiting, diarrhea, lacrimation, abdominal cramps, and piloerection. The family members report a history of substance use for the past month. The clinical presentation is due to what?

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Flashcards: Opioid Use Disorder

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_____ delirium is commonly associated with drug intoxication or withdrawl

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_____ delirium is commonly associated with drug intoxication or withdrawl

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Opioid Use Disorder - Free Indian Medical PG High-Yield