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Methanol/Ethylene Glycol Toxicity 

 

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Background

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  • Found in automotive coolant/antifreeze, windshield wiper fluid; may be ingested as substitute for ethanol (ex adulterated moonshine)

    • toxicity usually from ingestion (rarely from inhalation/dermal absorption)

  • Methanol & ethylene glycol ("parent drugs") are relatively nontoxic; mainly cause CNS sedation

    • Metabolites can cause profound toxicity (metabolized primarily by alcohol dehydrogenase - ADH)

      • Methanol → formate → retinal injury/blindness, ischemic/hemorrhagic injury to basal ganglia

      • Ethylene glycol → glycolate, glyoxylate, oxalate → acute renal failure

  • Early toxicity: CNS sedation/inebriation

  • Late toxicity: Anion gap metabolic acidosis, compensatory tachypnea/hyperpnea, coma, ocular toxicity (methanol) or renal failure (ethylene glycol)

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Management

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  • Secure airway prn

  • IV fluids, pressors prn

  • Investigations:

    • ABG/VBG

    • Lytes (incl Ca2+), creatinine/eGFR

    • Serum osmolality, serum [EtOH], serum methanol/ethylene glycol/isopropanol concentrations

    • Urinalysis (oxalate crystals)

  • Antidotes:

    • Fomepizole (inhibits ADH) 15 mg/kg IV loading dose, then 10 mg/kg q12hr x 4 doses. Can ↑ to 15 mg/kg q12 hr prn.

    • If fomepizole unavailable: ethanol 10 mL/kg of a 10% ethanol solution, then 1 mL/kg/hr of 10%. Titrate to serum ethanol concentration of 100 mg/dL (~22 mmol/L).

  • NaHCO3 if pH <7.3

  • Methanol poisoning: folic acid 50 mg IV q6 hrs

  • Ethylene glycol poisoning: thiamine 100 mg IV + pyridoxine 50 mg IV

  • Hemodialysis if severe toxicity

    • Metabolic acidosis

    • ↑ methanol/ethylene glycol concentrations (unless pH >7.3)

    • End-organ damage (visual changes, renal failure)

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References

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  • Ng, P.C.Y., Long, B.J., Davis, W.T. et al. Toxic alcohol diagnosis and management: an emergency medicine review. Intern Emerg Med 13, 375–383 (2018).

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