Benzodiazepine toxicity

Background

• Isolated benzodiazepine overdose has low morbidity/mortality
  • Coingestion or parenteral administration accounts for vast majority of deaths
  • Respiratory depression rare with overdose of oral agents

Clinical Features

• Somnolence, slurred speech, ataxia (similar to ETOH intoxication)
• Paradoxical reaction (more common in hyperactive children, psychiatric patients)
• Hypotension
• Respiratory depression

Differential Diagnosis

Sedative/hypnotic toxicity

• Absinthe
• Barbiturates
• Benzodiazepines
  • Flunitrazepam (Rohypnol)
• Chloral hydrate
• Gamma hydroxybutyrate (GHB)
• Baclofen toxicity
• Opioids
  • Lomotil toxicity
  • Loperamide toxicity
• Toxic alcohols
  • Ethanol
  • Ethylene glycol
  • Isopropyl alcohol
  • Methanol
• Xylazine toxicity

Evaluation

• Urine toxicology screen
  • Most benzodiazepine screens look for oxazepam, which is a metabolite of diazepam and chlordiazepoxide. Therefore, lorazepam, alprazolam, and clonazepam are commonly missed.
  • True positives: Oxazepam, temazepam, diazepam, alprazolam, triazolam
  • False negatives: Lorazepam, clonazepam, midazolam

Management

• GI decontamination
  • Activated Charcoal x1
• Mechanical ventilation if necessary

Flumazenil

• Controversial
  • May prevent need for mechanical ventilation; may precipitate benzo-withdrawal seizure
• Indication:
  • Consider (though controversial) for coma reversal
• Contraindications:
  • Suspected or known physical dependence on benzodiazepines
  • Suspected TCA overdose
  • Co-ingestion of seizure-inducing agents
  • Known seizure disorder
  • Suspected increased intracranial pressure
• Dosing
  • 0.2mg IV; may repeat q1min (max dose 3mg)
• Flumazenil-Induced Seizure
  • Treat with phenobarbital or propofol; benzodiazepines will not work

Disposition

• Consider discharge after 6hr observation

See Also

• Sedative/Hypnotic
• Benzodiazepines
• Benzodiazepine withdrawal