Gamma hydroxybutyrate toxicity: Difference between revisions
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==Clinical Features==
==Clinical Features==
''Classic Presentation: Young adult presents comatose and is intubated for airway protection and subsequently awakens while in the emergency department. When awake, can be safely discharged''
''Classic Presentation: Young adult presents comatose and is intubated for airway protection and subsequently awakens while in the emergency department. When awake, typically can be safely discharged.''
*CNS and respiratory depression  
*CNS depression; ataxia, nystagmus, somnolence, seizure, coma
*also cardiac and GI symptoms
**EEG may show no epileptiform changes
*often found to have co-intoxicants
*Respiratory depression; may also alternate between periods of apnea and hyperventilation
*usually young white male from nightclub
**Worse with other CNS depressants ([[alcohol]], [[benzodiazepines]], etc)
*may present with nausea and vomiting, respiratory depression, bradycardia, seizure
*Bradycardia, hypotension; ECG changes are rare
*may also have ataxia, nystagmus, somnolence and aggression
*Nausea and vomiting GI symptoms
*respiratory/CNS depression resolves abruptly
*Hypothermia
*respiratory depression worse with other CNS depressants ([[alcohol]], [[benzodiazepines]], etc)
*Often found to have co-intoxicants
*periods of apnea and hyperventilation
*Usually young white male from nightclub
*decreases respiratory rate but tidal volume increases so minute volume stable
*CNS and respiratory depression can resolve abruptly within minutes
*can also have seizure but EEG shows no epileptiform changes
**Patients may become aggressive upon waking
*bradycardia, hypotension
*ekg change occasionally but rare
*also get vomiting, hypothermia
===Clinical Course===
===Clinical Course===
*recover in 2-6 hrs
*Recover in 2-6 hours
*may be extubated and sent home  
*May be extubated and sent home  
*if longer than 6hr, look for other cause  
*If longer than 6 hours, look for other cause  
*can have cross tolerance with other drugs-alcohol and others that effect liver [[p450]] cytochome oxidase system
*Can have cross tolerance with other drugs-alcohol and others that effect liver [[p450]] cytochrome oxidase system


==Differential Diagnosis==
==Differential Diagnosis==

Revision as of 16:50, 24 April 2021

Background

  • Abbreviation: GHB
  • Frequently referred to as the "date rape drug"
  • Central nervous system depressant
  • GABA-B agonist (as opposed to GABA-A agonists - alcohol, benzodiazepines, etc)
  • Abused for:
    • Body building or sleep enhancement
    • euphoric, sexual, stimulant, and relaxant effects
    • Surreptitious drugging to facilitate sexual assault
  • Also used therapeutically in the treatment of narcolepsy[1]

Pharmacokinetics

  • Effects start in 15-20 minutes, peak in 30-60 minutes,
  • Lipid soluble, readily crosses the blood brain barrier
  • Elimination is dose-dependent; half-life of 20-50 minutes
  • The duration of GHB's clinical effects depends upon the dose, and ranges from 2.5-4 hours

Pharmacology

  • Is a metabolite and precursor of GABA
  • Interacts with GHB-specific receptors and also acts as a direct agonist of GABA-B receptors
  • Affects multiple neurotransmitter systems, including those of opioids, dopamine, serotonin, glutamate, and acetylcholine
  • Gamma butyrolactone (GBL) and 1,4 butanediol (BD) are GHB analogs that are rapidly metabolized to GHB after ingestion, with the same toxic and recreational effects

Clinical Features

Classic Presentation: Young adult presents comatose and is intubated for airway protection and subsequently awakens while in the emergency department. When awake, typically can be safely discharged.

  • CNS depression; ataxia, nystagmus, somnolence, seizure, coma
    • EEG may show no epileptiform changes
  • Respiratory depression; may also alternate between periods of apnea and hyperventilation
  • Bradycardia, hypotension; ECG changes are rare
  • Nausea and vomiting GI symptoms
  • Hypothermia
  • Often found to have co-intoxicants
  • Usually young white male from nightclub
  • CNS and respiratory depression can resolve abruptly within minutes
    • Patients may become aggressive upon waking

Clinical Course

  • Recover in 2-6 hours
  • May be extubated and sent home
  • If longer than 6 hours, look for other cause
  • Can have cross tolerance with other drugs-alcohol and others that effect liver p450 cytochrome oxidase system

Differential Diagnosis

Sedative/hypnotic toxicity

Drugs of abuse

Diagnosis

  • Not detectable on rapid urine drug screens
  • Definitive diagnosis requires gas chromatography
  • ED physicians are not accurate in diagnosing clinically

Management

  • supportive
  • look for coingestants and occult trauma
  • charcoal not helpful since rapidly absorbed and since can vomit and aspirate
  • protein bound so can use dialysis*but so short course usually do not need.

Antidotes

Disposition

See Also

References

  1. ↑ Mamelak M, Scharf MB, Woods M. Treatment of narcolepsy with gamma-hydroxybutyrate. A review of clinical and sleep laboratory findings. Sleep. 1986;9(1 Pt 2):285-289. doi:10.1093/sleep/9.1.285
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