- Published on
Toxicology – Methanol (Toxic Alcohol Exposure)
Source
Methanol is found in products such as antifreeze, windshield washer fluid, paint removers, fuels, cleaning agents, and improperly distilled alcohol (e.g., moonshine).
Typical Presentation
Patients often present hours after ingestion. Early symptoms may resemble simple intoxication, followed by a temporary symptom-free period before more severe toxicity develops—especially visual complaints.
Clinical Features
Methanol poisoning typically progresses through several stages:
Methanol itself is not highly toxic, but it is metabolized in the liver into formaldehyde and then formate. Formate is the primary toxic compound, causing mitochondrial dysfunction, metabolic acidosis, and selective damage to the optic nerve and brain.
Management
Treatment aims to block formation of toxic metabolites and remove methanol from the body:
Source
Methanol is found in products such as antifreeze, windshield washer fluid, paint removers, fuels, cleaning agents, and improperly distilled alcohol (e.g., moonshine).
Typical Presentation
Patients often present hours after ingestion. Early symptoms may resemble simple intoxication, followed by a temporary symptom-free period before more severe toxicity develops—especially visual complaints.
Clinical Features
Methanol poisoning typically progresses through several stages:
- Early (CNS) phase (30–120 minutes): Mild intoxication, poor coordination, drowsiness, slurred speech, and possible coma in severe cases.
- Latent phase (8–24 hours): Temporary improvement or absence of symptoms.
- Metabolic phase: Headache, nausea, vomiting, and development of a high anion gap metabolic acidosis with an increased osmolal gap.
- Ocular phase (12–48 hours): Visual disturbances such as blurred vision, light sensitivity, “snowfield” vision, and potential permanent blindness.
Methanol itself is not highly toxic, but it is metabolized in the liver into formaldehyde and then formate. Formate is the primary toxic compound, causing mitochondrial dysfunction, metabolic acidosis, and selective damage to the optic nerve and brain.
Management
Treatment aims to block formation of toxic metabolites and remove methanol from the body:
- Fomepizole is the preferred antidote; it inhibits alcohol dehydrogenase.
- Ethanol may be used as an alternative if fomepizole is unavailable.
- Hemodialysis is indicated in severe cases (e.g., high methanol levels, acidosis, or organ damage) to rapidly remove toxin and metabolites.
- Folic or folinic acid helps enhance metabolism of formate into non-toxic substances.
- Sodium bicarbonate is used to correct metabolic acidosis.
- Visual symptoms are a hallmark of methanol toxicity.
- Even small amounts can cause severe poisoning.
- Co-ingestion of ethanol may delay toxicity by competing for metabolism.
- Early treatment is critical to prevent permanent vision loss and death.
0 Comments
