Activated charcoal is an adsorbent commonly used in the management of both human and veterinary poisoning. Charcoal is treated to produce activated charcoal, a finely powdered material with a huge surface area which is capable of binding to a variety of chemicals; this relies mainly on weak intermolecular forces and generally non-polar materials are not well bound. Activated charcoal is given orally and passes through the gut reducing or preventing systemic toxicity of the ingested substance.
The use of activated charcoal in a particular case will depend on the substance ingested. A single dose is most useful when the substance ingested is still in the stomach and in most cases that is all that is required. Note that for a single dose of activated charcoal to be effective in reducing absorption, it must be in direct contact with the ingested substance and therefore must be given as soon as possible after ingestion. It is inappropriate to give activated charcoal hours after ingestion in most cases. Repeat dose administration of activated charcoal is appropriate for some poisons and is thought to act by interrupting enterohepatic recycling (such as theobromine in chocolate) and/or promoting drug exsorption from the systemic circulation into the gut lumen. Repeat doses may also be useful for drugs formulated as sustained or modified release.
It is important to note that some formulations of activated charcoal contain a cathartic, to decrease intestinal transit time. It is important to consider which formulation/product to use in a specific case, as repeat doses of a cathartic-containing formulations can lead to dehydration and electrolyte imbalance. We are able to advise on a case-by-case basis, which formulation/dose is required and whether administration of repeat dose activated charcoal is appropriate.