DESCRIPTION

Activated charcoal binds a wide array of compounds and thereby prevents their absorption.

FORMS AND USES

• Substances included are activated charcoal (Actidose, Actidose-Aqua, Insta-Char, Liqui-Char), activated carbon, and adsorbent charcoal. Some products are premixed with a cathartic.
• Activated charcoal is used in gastrointestinal decontamination to bind adsorb poison.
• It is also used to enhance elimination of some drugs (e.g., phenobarbital).

MECHANISM OF ACTION

• Activated charcoal is created by steam or chemical activation of wood pulp (heating in the presence of an oxidizing gas or dehydrating agent). The result is a highly porous material with a very large surface area. Surface area varies in commercial products from 950 to 1,500 m²/g.
• Most drugs and other chemicals bind to the walls of the pores in activated charcoal, thereby reducing the material available for adsorption into the bloodstream. Adsorption is reversible, but desorption occurs slowly.
• Nondissociated salts and low-water soluble compounds are best adsorbed. Small, ionized compounds and highly water-soluble compounds are the most poorly adsorbed.
• Substances that undergo enterohepatic circulation or are secreted into the gastrointestinal tract may undergo enhanced elimination by repeated-dose activated charcoal.

DRUG AND DISEASE INTERACTIONS

• Charcoal will adsorb some orally administered antidotes.
• Repeat-dose activated charcoal may remove significant quantities of therapeutic medications from the body (e.g., anticonvulsants).

PREGNANCY AND LACTATION

Activated charcoal is not absorbed into the body and should not have any effect on pregnancy.

Section Outline:

• DESCRIPTION
• FORMS AND USES
• MECHANISM OF ACTION
• DRUG AND DISEASE INTERACTIONS
• PREGNANCY AND LACTATION

SINGLE-DOSE THERAPY

• Agents bound by charcoal
  • Nearly all chemicals and drugs are bound by activated charcoal. Thus, activated charcoal should be administered unless it is known that the drug ingested is not bound by charcoal.
  • Patients often ingest multiple agents. Activated charcoal is usually indicated if any of the drugs are adsorbed by charcoal (e.g., a lithium and phenytoin ingestion).
• Substances for which activated charcoal administration has not been shown to be clinically effective include mineral acids, mineral bases, ethanol, arsenic, boric acid, bromide, fluoride, iron, iodide, ipecac, lithium, and potassium.
• The appropriate time to administer activated charcoal is controversial. In general, a single dose is recommended if a substantial ingestion has occurred within the previous few hours. It is also recommended even later, if the patient has clinical manifestations. This suggests that adsorption is ongoing and activated charcoal may limit further absorption.

MULTIPLE-DOSE THERAPY

• Although the elimination of several substances is increased by activated charcoal, there is no drug for which clinical efficacy has been proven.
• In general, multiple-dose therapy is recommended in cases of phenobarbital and theophylline intoxication.
• Other commonly proposed indications for multiple-dose therapy include ingestion of sustained-release formulations and when bezoar formation is suspected (e.g., rising salicylate levels despite appropriate decontamination and urinary alkalinization).
• Enhanced elimination, but not clinical efficacy, has been demonstrated for carbamazepine, chlordecone, cyclosporine, dapsone, digitoxin, meprobamate, nadolol, phenylbutazone, phenytoin, quinine, salicylate, and valproic acid.
• Owing to the increased frequency of complications and lack of proven clinical efficacy, multiple-dose therapy is discouraged.

Section Outline:

• SINGLE-DOSE THERAPY
• MULTIPLE-DOSE THERAPY

CONTRAINDICATIONS

• Repeat-dose activated charcoal is contraindicated in patients with known bowel obstruction or ileus.
• It should be used with caution in patients with diminished bowel sounds or following ingestion of agents known to produce ileus.

ADVERSE EFFECTS

• Emesis occurs in about 15% of cases but is not usually recurrent; however, it may lead to further complications:
  • Pulmonary injury may result if hydrocarbons have been ingested and aspiration occurs.
  • Esophageal injury may be increased when corrosives have been ingested.
  • Aspiration pneumonitis may occur.
• Aspiration of charcoal may cause airway obstruction and bronchiolitis obliterans.
• Activated charcoal may obscure the endoscopic visualization of gastroesophageal injury.
• Constipation, bowel obstruction, and charcoal bezoars have been reported in patients who have ingested agents that decrease gastrointestinal motility. However, this appears to occur more commonly during multiple-dose administration.
• Bowel perforation has occurred.
• Corneal abrasions may occur following eye contamination with activated charcoal.

Section Outline:

• CONTRAINDICATIONS
• ADVERSE EFFECTS

SINGLE-DOSE USE

• A dose of 1 to 2 g/kg administered orally is recommended. If patient is unable to drink, activated charcoal may be administered via nasogastric tube. Patients who are obtunded or have a depressed gag reflex should be intubated prior to administration.
• A second dose of activated charcoal administered 2 to 3 hours after the initial dose may be advisable in some circumstances in order to assure binding as much of the ingested toxicant as possible. This may include:
  • Drugs with prolonged absorption phase or slow dissolution (sustained-release or enteric-coated medications)
  • Agents with anticholinergic effects (tricyclic antidepressants, phenothiazine, and some plants)
  • Drugs that form concretions or bezoars (salicylate and carbamazepine).
• Activated charcoal is administered as a slurry of 30 g of activated charcoal in 240 cc of liquid.
• A saline cathartic or sorbitol may be used with the first dose, although there is no reported evidence that this increases effectiveness. Cathartics that have been used with activated charcoal include:
  • Magnesium or sodium sulfate: Adult 20 to 30 g/dose; child 250 mg/kg/dose
  • Magnesium citrate: adult or child 4 cc/kg/dose, up to 300 cc/dose
  • Sorbitol: adult 1 to 2 g/kg/dose, up to 150 g/dose; child: 1 to 1.5 g/kg/dose, up to 50 gfdose
• If the patient vomits charcoal within 1 hour, half of the original dose should be administered. Aggressive antiemetic therapy may be required for repetitive vomiting:
  • Adult: metoclopramide 1.0 to 2.0 mg/kg intravenously plus prochlorperazine 10 mg intravenously or droperidol 1.25 to 2.5 mg intravenously.
  • Diphenhydramine 25 to 50 mg intravenously may be added to this regimen.

MULTIPLE-DOSE USE

• When the decision has been made to use multiple-dose activated charcoal, a repeat dose may be administered every 2 to 6 hours. A uniform dose has not been established. Suggested regimens include:
  • 0.5 g/kg every 2 to 4 hours
  • 20 g every 2 hours, 40 g every 4 hours, or 60 g every 6 hours.
• The duration of therapy has not been established. A typical approach is to continue it for 24 to 48 hours.
• Continuous nasogastric instillation of activated charcoal, 0.25 to 0.5 g/kg/h, has been advocated to reduce the incidence of emesis.
• When the first dose of activated charcoal is combined with a cathartic, subsequent doses should not be given with a cathartic because of the risk of fluid and electrolyte disorders. Note that some charcoal products already contain a cathartic.

Section Outline:

• SINGLE-DOSE USE
• MULTIPLE-DOSE USE

PEDIATRIC

• Children are more susceptible to the fluid and electrolyte disorders that can result from cathartic use.
• Small airway size increases the risk of airway compromise following aspiration.

GERIATRIC

• Older patients are more likely to have gastrointestinal motility disorders.
• They are also more likely to be on therapeutic medications that may be removed from the body by repeat-dose activated charcoal.

Section Outline:

• PEDIATRIC
• GERIATRIC

Poisoning by agents primarily affecting the gastrointestinal system.

RECOMMENDED READING

Al-Shareef AH, Buss DC, Allen EM, et al. The effects of charcoal and sorbitol (alone and in combination) on plasma theophylline concentrations after sustained-release formulation. Hum Exp Toxicol 1990;9:179-182.

Chin L, Picchioni AL, Duplisse BR. Action of activated charcoal on poisons in the digestive tract. Toxicol Appl Pharmacol 1970;16:786.

Neuvonen PJ, Olkolla KT. Oral activated charcoal in the treatment of acute toxic ingestions. Ann Emerg Med 1989;18:101-104.

Author: Steven A. Seifert

Reviewer: Katherine M. Hurlbut