Activated Charcoal
Introduction
A charcoal is "activated" during preparation through chemical processes, including blasting it with steam or hot air.
- These processes increase the surface area of the charcoal particles by increasing pore size. With a huge surface area, more poison can be absorbed.
Uses
Activated charcoal powder for suspension is often prescribed as decontaminant for the majority of poisoning except for poisonings with alcohols (e.g. ethanol, methanol), strong acids or alkalis, potassium chloride, or metals (gold, lithium, iron, potassium). It is recommended usually for patients presenting within 1 hour of ingestion of a clinically significant amount of a substance that is absorbed by charcoal.
- The affinity of a substance for activated charcoal is actually determined by its ionic status and its solubility in water.
- The weak Van der Waals forces adsorbed molecules onto the surface of charcoal as they travel through the gut, reducing their absorption into the circulation.
As per Ministry of Health Medicines Formulary, activated charcoal 250 mg tablet is indicated for diarrhoea and food poisoning. The dose is 0.5-1 g given 3-4 times.
NOTE: Activated charcoal capsules and tablets should not be used for the emergency treatment of acute poisoning.
Dressings containing activated charcoal are used to absorb odours from wounds. There are limited studies suggesting accelerated wound healing with activated charcoal dressing with or without silver.
Cautions
Activated charcoal is relatively non-toxic when given orally but gastrointestinal disturbances such as vomiting, constipation, or diarrhoea have been reported. It may colour the faeces, tongue, and mucous membranes black.
Activated charcoal should be used with caution in patients at risk of gastrointestinal obstruction as it may reduce gastrointestinal motility. It has been associated with intestinal obstruction and perforation after multiple dosing.
Activated charcoal has the potential to reduce the absorption of many drugs from the gastrointestinal tract and simultaneous oral therapy should therefore be avoided.
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