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Toxicology – Gamma-Hydroxybutyrate (GHB) Toxicity
Source
GHB is a synthetically produced compound available as a powder or dissolved liquid. Related substances such as gamma-butyrolactone (GBL) act as prodrugs and are converted into GHB in the body.
Typical Presentation
Exposure often occurs in social settings. Individuals may suddenly lose consciousness after ingestion, with rapid recovery hours later and little to no memory of events.
Clinical Features
At lower doses, GHB produces euphoria, disinhibition, and sedative effects. Higher doses can lead to central nervous system depression, amnesia, and coma. Additional findings may include bradycardia, hypotension, hypothermia, respiratory depression, seizures, and myoclonus. Coingestion with alcohol significantly increases the risk of severe toxicity and respiratory arrest. A characteristic feature is abrupt awakening after several hours due to a rebound effect.
Mechanism of Action
GHB is structurally related to GABA and readily crosses the blood–brain barrier. It acts on specific GHB receptors and, at higher concentrations, also stimulates GABA receptors. These effects increase dopamine release initially and then suppress neuronal activity, leading to sedation and coma. A rebound increase in dopamine may occur several hours after ingestion, explaining sudden recovery.
Management
Treatment is supportive, with early attention to airway protection and ventilation. There is no specific antidote. Agitated patients may require sedation, and benzodiazepines are used for seizure control.
Key Points
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Source
GHB is a synthetically produced compound available as a powder or dissolved liquid. Related substances such as gamma-butyrolactone (GBL) act as prodrugs and are converted into GHB in the body.
Typical Presentation
Exposure often occurs in social settings. Individuals may suddenly lose consciousness after ingestion, with rapid recovery hours later and little to no memory of events.
Clinical Features
At lower doses, GHB produces euphoria, disinhibition, and sedative effects. Higher doses can lead to central nervous system depression, amnesia, and coma. Additional findings may include bradycardia, hypotension, hypothermia, respiratory depression, seizures, and myoclonus. Coingestion with alcohol significantly increases the risk of severe toxicity and respiratory arrest. A characteristic feature is abrupt awakening after several hours due to a rebound effect.
Mechanism of Action
GHB is structurally related to GABA and readily crosses the blood–brain barrier. It acts on specific GHB receptors and, at higher concentrations, also stimulates GABA receptors. These effects increase dopamine release initially and then suppress neuronal activity, leading to sedation and coma. A rebound increase in dopamine may occur several hours after ingestion, explaining sudden recovery.
Management
Treatment is supportive, with early attention to airway protection and ventilation. There is no specific antidote. Agitated patients may require sedation, and benzodiazepines are used for seizure control.
Key Points
- GHB has a characteristic salty taste when mixed in beverages.
- It is available medically in some settings for treatment of narcolepsy with cataplexy.
- Certain products have historically contained GHB or its precursors, leading to accidental poisonings.
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