Introduction
Alcohols like ethyl alcohol (ethanol) and methyl alcohol (methanol) are widely encountered in clinical practice. Ethanol is used socially and medically, while methanol is highly toxic and responsible for accidental or adulterated liquor poisoning. Understanding their actions, dangers and treatment is essential in medical care.
Alcohol (Ethanol)
Ethanol is a central nervous system depressant. It follows zero-order kinetics, meaning a fixed amount is eliminated per hour regardless of concentration. Chronic use induces liver enzymes, especially CYP2E1, which increases the toxicity of drugs like paracetamol.
Because alcohol is exhaled through lungs, it can be detected with a breath analyser.
Therapeutic Uses of Alcohol
- Antiseptic: 70% ethanol is widely used on skin before injections and surgical procedures. It should not be applied on open wounds or mucosa as it is irritating.
- Trigeminal and other neuralgias: Injecting alcohol into a nerve trunk destroys nerve fibres and relieves pain.
- Preventing bedsores: Used externally in bedridden patients.
- Methanol poisoning: Ethanol competes with methanol for metabolism and prevents formation of toxic metabolites.
- Reducing fever: Alcohol sponges help lower body temperature.
Acute Ethanol Intoxication
Acute overdose is a medical emergency. Common symptoms include:
- Drowsiness, confusion
- Nausea and vomiting
- Ataxia and slurred speech
- Respiratory depression
- Hypoglycaemia
- Hypotension
Treatment
The main goal is to maintain airway, breathing and circulation (ABC).
- Stabilise airway, provide oxygen and correct fluids and electrolytes
- Gastric lavage if needed
- Intravenous glucose to correct low blood sugar
- IV thiamine to prevent Wernicke’s encephalopathy
- Haemodialysis in severe cases
Alcohol Withdrawal Syndrome
Stopping alcohol suddenly in dependent individuals causes withdrawal due to CNS hyperexcitability.
Symptoms
- Restlessness and tremors
- Insomnia and anxiety
- Nausea and vomiting
- Hallucinations and delirium tremens
- Convulsions
Treatment
- Benzodiazepines (diazepam, chlordiazepoxide) to control agitation, tremors and seizures
- Psychological and social support
Management of Chronic Alcoholism
Long-term treatment includes counselling, therapy and medications.
Drugs Used
- Disulfiram: Produces an unpleasant reaction with alcohol (acetaldehyde syndrome), causing flushing, vomiting, headache, hypotension and palpitations. Helps maintain abstinence.
- Naltrexone: Reduces craving and prevents relapse.
- Acamprosate: Acts on GABA receptors and reduces relapse rate.
- Ondansetron: Useful in early-stage alcohol dependence.
- Topiramate: Helps reduce craving.
Several drugs like metronidazole, griseofulvin and cefoperazone can produce disulfiram-like reactions. Patients must avoid alcohol while taking them.
Methanol (Methyl Alcohol)
Methanol, also called wood alcohol, is extremely toxic. Poisoning occurs due to ingestion of methylated spirit, industrial alcohol or adulterated liquor.
Why Methanol Is Dangerous
Methanol itself is only a mild CNS depressant, but its metabolites—formaldehyde and formic acid—cause severe toxicity.
Symptoms of Methanol Poisoning
- Nausea, vomiting and abdominal pain
- Headache and vertigo
- Confusion and convulsions
- Hypotension and coma
- Metabolic acidosis
- Visual disturbances, dim vision, retinal damage and blindness
Treatment of Methanol Poisoning
- Keep patient in a dark room to protect eyes.
- Maintain airway, breathing and circulation.
- Gastric lavage after securing airway.
- IV sodium bicarbonate to correct metabolic acidosis.
- Ethanol therapy: Ethanol competes with methanol for alcohol dehydrogenase, preventing toxic metabolite formation.
- Fomepizole: Preferred drug; inhibits alcohol dehydrogenase and has fewer CNS effects.
- Calcium leucovorin: Enhances metabolism of formate and protects retina.
- Haemodialysis: Removes methanol and its metabolites rapidly.
Detailed Notes:
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