Sedative/hypnotic toxicity

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

Toxic Alcohols Anion/Osmolar Gaps

Substance	Osmolar gap	Metabolic acidosis	Anion gap	Ketones	Ca Oxalate crystals	Reduced vision	Management
Ethanol	+	+/- (if ketoacidosis)	+/- (if ketoacidosis)	+/-	-	-	Mainly supportive
Ethylene glycol	+ (early)*	+	+	-	+	-	Fomepizole, Thiamine, Pyridoxine, +/- Dialysis
Methanol	+ (early)*	+	+	-	-	+	Fomepizole or ethanol, Folinic acid/Folic acid, +/- Dialysis
Isopropyl alcohol	+	-	-	+ (acetonemia without acidosis)	-	-	Mainly supportive, +/- Dialysis if severe
Propylene glycol	+	+	+ (lactic acidosis)	-	-	-	D/C offending agent (e.g. IV lorazepam/diazepam), supportive, +/- Dialysis

• Osmolar gap → Anion gap transition: For all toxic alcohols, the osmolar gap is elevated early (parent compound present) and decreases over time as the alcohol is metabolized into organic acid metabolites, which then produce an anion gap metabolic acidosis. A normal osmolar gap does NOT exclude toxic alcohol ingestion if presentation is delayed.

Key distinguishing features

• Isopropyl alcohol: The only toxic alcohol that causes ketosis without metabolic acidosis (metabolized to acetone, not an organic acid)
• Ethylene glycol: Ca oxalate crystals in urine + anion gap metabolic acidosis + renal failure
• Methanol: Visual disturbances (blurred vision, "snowfield" vision, blindness) + anion gap metabolic acidosis + optic disc hyperemia on fundoscopy

Toxidrome Chart

Finding	Cholinergic	Anticholinergic	Sympathomimetic	Sympatholytic^	Sedative/Hypnotic
Example	Organophosphates	TCAs	Cocaine	Clonidine	ETOH
Temp	Nl	Nl / ↑	Nl / ↑	Nl / ↓	Nl / ↓
RR	Variable	Nl / ↓	Variable	Nl / ↓	Nl / ↓
HR	Variable	↑	↑ (sig)	Nl / ↓	Nl / ↓
BP	↑	↑	↑	Nl / ↓	Nl / ↓
LOC	Nl / Lethargic	Nl, agitated, psychotic, comatose	Nl, agitated, psychotic	Nl, Lethargic, or Comatose	Nl, Lethargic, or Comatose
Pupils	Variable	Mydriatic	Mydriatic	Nl / Miotic
Motor	Fasciculations, Flacid Paralysis	Nl	Nl / Agitated	Nl
Skin	Sweating (sig)	Hot, dry	Sweating	Dry
Lungs	Bronchospasm / rhinorrhea	Nl	Nl	Nl
Bowel Sounds	Hyperactive (SLUDGE)	↓ / Absent	Nl / ↓	Nl / ↓

^Consider Sympatholytic when looking at Sedative OD or someone who doesn't respond to Narcan

Withdrawal from substances have the opposite effect

See Also

• Toxicology (Main)