Isopropyl alcohol toxicity

Background
  • Main component of rubbing alcohol
  • Hallmark is osmolar gap, ketosis, that is without acidosis
    • Metabolized to acetone, not to an acid
  • Takes 30-60 min for acetone to appear in blood; 3 hr to appear in urine
  • Lethal Dose: 4-8 g/kg or 250 mL in average adult (calculated using volume of pure isopropyl alcohol)
    • Typical store bought rubbing alcohol is 70% isopropyl alcohol by volume, so lethal dose is ~ 350 mL

Pharmacology[1]
  • Unlike other toxic alcohols (methanol, ethylene glycol), toxic effects caused by parent agent (IA) rather than metabolite (acetone)
  • Metabolized to acetone by alcohol dehydrogenase
  • Maximal distribution in ≤ 2 hours
  • Lethal dose > 200 mg/dL, although variable literature

Clinical Features
  • CNS depression
    • Similar to ETOH intoxication, but longer-lasting
    • Usually peaks in first hour of ingestion
  • GI
  • Respiratory depression
    • Fruity breath from acetone
  • Hypotension, hypothermia from peripheral vasodilation
  • Hypoglycemia (in malnourished patients)

Differential Diagnosis

Sedative/hypnotic toxicity

Evaluation

Work-Up
  • Fingerstick glucose
  • Complete metabolic panel
  • Serum ketones
  • Serum Osmolality
  • Uinarlysis
  • VBG
  • Aspirin/Tylenol levels
  • ECG
  • Serum isopropyl alcohol level (if available)
  • Total CK

Evaluation
  • Osmolal gap > 10; see Osmolal or Osmolar Gap
  • Absence of anion gap
  • Absence of metabolic acidosis
  • Absence of serum beta hydroxybutyrate
  • Presence of serum and urine ketones
    • Consider other diagnosis if absent 2hr after ingestion
  • Creatinine may be falsely elevated due to acetone interference with laboratory measurement of Cr

Toxic Alcohols Anion/Osmolar Gaps
Osmolar gap Anion gap
Ethanol + + if ketoacidosis
Ethylene glycol + +
Methanol + +
Isopropyl alcohol + -

Management
  • Treatment is supportive.
  • No role for fomepizole or ethanol
    • Blockade of alcohol dehydrogenase (ADH) will prolong intoxication
  • Hemodialysis indications:
    • Hypotension
    • Comatose
    • Consider if IA serum level >200mg/dL

Disposition
  • Generally may be discharged once clinically sober.

See Also

References
  1. Kraut JF, Kurtz I. Clin J Am Soc Nephrol 2008. PMID: 18045860
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