Ethylene Glycol and Other Toxic Alcohol Poisoning ✅ Flashcards
What are the characteristics of ethylene glycol?
- Odourless
- Sweet tasting
What happens if ethylene glycol is ingested?
Has significant toxicity, even in small amounts
What volume of ethylene glycol ingested can have significant toxicity in a 20kg child?
<5ml
What is ethylene glycol metabolised into?
Glycoaldehyde
What enzyme is involved in the metabolism of ethylene glycol to glycoaldehyde?
Alcohol dehydrogenase
What is glycoaldehyde metabolised into?
Glycolic acid
What enzyme is involved in the metabolism of glycoaldehyde to glycolic acid?
Aldehyde dehydrogenase
What is glycolic acid metabolised into?
Glyoxylic acid
What enzyme is involved in the metabolism of glycolic acid to glyoxylic acid?
Lactate dehydrogenase
What is glyoxylic acid metabolised into?
Oxalic acid
What enzyme is involved in the metabolism of glyoxylic acid to oxalic acid?
Xanthine oxidase
What are the phases of ethylene glycol poisoning?
- 0.5-12 hours
- 12-36 hours
- 24-72 hours
What happens 0.5-12 hours after ethylene glycol ingestion?
Intoxicated appearance;
- Dizziness
- Incoordination
- Slurred speech
- Confusion
- Nausea/vomiting
What causes the symptoms 0.5-12 hours following ethylene glycol ingestion?
Unmetabolised ethylene glycol
What is seen 12-36 hours after ethylene glycol ingestion?
- Tachycardia
- Hypertension
- Raised anion gap metabolic acidosis with compensatory hyperventilation
What causes the clinical features 12-36 hours after ethylene glycol ingestion?
Accumulation of glycolic and oxalic acid
What is seen 24-72 hours after ingestion of ethylene glycol?
Signs and symptoms of renal failure
What causes renal failure in ethylene glycol poisoning?
Probably deposition of calcium oxalate crystals in the kidney
What are the antidotes to ethylene glycol poisoning?
- Alcohol
- Fomepizole
How does alcohol act as an antidote to ethylene glycol?
It has a much higher affinity for alcohol dehydrogenase than ethylene glycol
How does fomepizole act as an antidote to ethylene glycol?
It is a potent inhibitor of alcohol dehydrogenase
How does the prevention of metabolism of ethylene glycol by alcohol or fomepizole reduce toxicity of ethylene glycol?
It prevents formation of toxic metabolites, and ethylene glycol is gradually excreted unchanged in the urine
What are the advantages of fomepizole over alcohol in ethylene glycol poisoning?
It does not cause intoxication or hypoglycaemia
What is the disadvantage of fomepizole over alcohol in the treatment of ethylene glycol poisoning?
It is significantly more expensive
What other substance can alcohol or fomepizole be used as the antidote for?
Methanol
Why can alcohol or fomepizole also be used as the antidote for methanol poisoning?
Methanol is also metabolised by alcohol dehydrogenase
What is methanol metabolised into with alcohol dehydrogenase?
Formaldehyde
What is formaldehyde metabolised into?
Formic acid
What enzyme is involved in the metabolism of formaldehyde into formic acid?
Aldehyde dehydrogenase
What is formic acid metabolised into?
CO2 + H2O
