Hallucinogen-Related Disorders

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Hallucinogens Overview - Trippy Toxins Taxonomy

  • Definition: Psychoactive agents causing profound alterations in perception (hallucinations, illusions), mood, and cognition. Effects are highly variable.
  • Key Classes & Examples:
    • Indoleamines (Serotonergic):
      • LSD (Lysergic acid diethylamide) - potent, synthetic.
      • Psilocybin (from 'magic mushrooms') - natural.
      • DMT (Dimethyltryptamine) - natural/synthetic.
      • Mechanism: Primarily 5-HT2A receptor agonists.
    • Phenylethylamines:
      • Mescaline (from peyote cactus) - natural.
      • DOM (2,5-Dimethoxy-4-methylamphetamine) - synthetic.
      • MDMA (Ecstasy) - synthetic, also stimulant.
    • Dissociative Anesthetics:
      • PCP (Phencyclidine) - synthetic.
      • Ketamine - synthetic, medical use.
      • Mechanism: NMDA receptor antagonists.
    • Anticholinergics (Deliriants): Datura, Atropine (plant-derived). Mechanism of Hallucinogens at 5HT2A Receptors, and typical examples)

⭐ Examples: LSD, Psilocybin (mushrooms), Mescaline (peyote), DMT, PCP, Ketamine.

Mechanisms of Action - Brain's Serotonin Symphony

  • Classical Hallucinogens (LSD, Psilocybin, Mescaline):
    • Primarily act as agonists at serotonin 5-HT2A receptors.
    • Also affect other 5-HT receptors (e.g., 5-HT1A, 5-HT2C).
    • Leads to ↑glutamate release in prefrontal cortex (PFC).

⭐ Classical hallucinogens (LSD, psilocybin, mescaline) primarily act as agonists at serotonin 5-HT2A receptors.

  • Dissociative Anesthetics (PCP, Ketamine):
    • Non-competitive antagonists at NMDA glutamate receptors.
    • Block glutamate action, leading to dissociative effects.
    • May also interact with dopamine, opioid, and sigma receptors.
  • Atypical Hallucinogens (e.g., Salvinorin A):
    • Potent and selective agonist at kappa-opioid receptors.
    • Unique mechanism, distinct from classical or dissociative types.

5-HT2A Receptor Activation by Hallucinogens

Clinical Features & Intoxication - Perceptual Kaleidoscope

  • General Intoxication Features:

    • Perceptual Distortions: Vivid visual, auditory, tactile hallucinations; illusions; synesthesia (e.g., "seeing sounds"); distorted time/space perception.
    • Mood & Thought: Marked anxiety or depression, panic ("bad trip"), euphoria, paranoia, grandiosity, depersonalization, derealization, impaired judgment.
    • Somatic (Sympathomimetic): Mydriasis (dilated pupils), tachycardia, hypertension, hyperthermia, sweating, palpitations, tremors, incoordination, nausea.
  • Classic Hallucinogens (e.g., LSD, Psilocybin, Mescaline):

    • Key: Predominantly perceptual changes, mood alteration.
    • Physical: Significant mydriasis, ↑HR, ↑BP.
    • "Good trip" (euphoria, mystical experiences) vs. "Bad trip" (intense anxiety, fear, psychosis-like state).
  • Dissociative Anesthetics (e.g., Phencyclidine [PCP], Ketamine):

    • Key: Dissociation, analgesia, amnesia.
    • Behavioral: Agitation, aggression, impulsivity, unpredictable violence, bizarre behavior, psychosis.
    • Neurological: Nystagmus (vertical, horizontal, or rotatory - classic for PCP), ataxia, dysarthria, muscle rigidity, hyperacusis.
    • Severe: Seizures, coma, rhabdomyolysis, respiratory depression.

⭐ Phencyclidine (PCP) intoxication is uniquely associated with nystagmus (rotatory, horizontal, or vertical) and aggressive, violent behavior.

Management & Specific Syndromes - Navigating the Trip

  • General Mgmt:
    • Supportive: Reassurance, "talk-down" technique, quiet, low-stimulus environment.
    • Agitation/Anxiety: Benzodiazepines (e.g., Lorazepam, Diazepam).
    • Severe Psychosis: If Benzodiazepines fail, consider antipsychotics (e.g., Haloperidol) cautiously.
  • PCP Specifics:
    • Key: Manage hyperthermia, rhabdomyolysis, seizures.
    • Benzodiazepines for agitation/seizures. Avoid phenothiazines (↓seizure threshold).
  • HPPD & Flashbacks:
    • HPPD: Persistent perceptual disturbances post-cessation.
    • Flashbacks: Episodic recurrences.
    • Tx: Reassurance; Benzodiazepines, SSRIs if distressing.

⭐ Hallucinogen Persisting Perception Disorder (HPPD) involves re-experiencing perceptual distortions after cessation of use, without current intoxication.

High‑Yield Points - ⚡ Biggest Takeaways

  • Hallucinogens (LSD, psilocybin) cause perceptual distortions, visual hallucinations, and synesthesia.
  • PCP intoxication features nystagmus (rotatory/vertical), aggression, ataxia, and muscle rigidity.
  • Hallucinogen Persisting Perception Disorder (HPPD) involves recurrent flashbacks of perceptual disturbances.
  • Management is mainly supportive care; benzodiazepines for agitation or PCP-induced symptoms.
  • Classic hallucinogens (LSD) typically lack a significant withdrawal syndrome; PCP may have one.
  • PCP can cause severe complications like hypertension, hyperthermia, and rhabdomyolysis.

Practice Questions: Hallucinogen-Related Disorders

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What is the drug that produces dissociative anesthesia?

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Flashcards: Hallucinogen-Related Disorders

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A type of tactile hallucination seen in chronic users of _____ where they feel as if grains of sand are lying under the skin or insects are creeping on the skin (formication), also known as Magnan syndrome

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A type of tactile hallucination seen in chronic users of _____ where they feel as if grains of sand are lying under the skin or insects are creeping on the skin (formication), also known as Magnan syndrome

cocaine

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