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Introduction

  1. Pharmacology. Activated charcoal, by virtue of its large surface area, adsorbs many drugs and toxins. Highly ionic salts (eg, iron, lithium, and cyanide) and small polar molecules (eg, alcohols) are poorly adsorbed. Multi-dose activated charcoal (MDAC) can increase the rate of elimination of some drugs that have a small volume of distribution and that undergo enterogastric or enterohepatic recirculation (eg, digitoxin) or diffuse into the GI lumen from the intestinal circulation (eg, phenobarbital and theophylline). See also discussion in Section I, Table I-36. Coadministration with cathartics is of unproven benefit and is associated with risks (see Table I-37).
  2. Indications
    1. Activated charcoal is often used orally after an ingestion to limit drug or toxin absorption, although there is debate concerning its routine use. It is most likely useful if given within 1 hour of an ingestion, but effectiveness is subject to numerous variables (eg, charcoal-to-substance ratio, contact time, pH, substance solubility, and whether the ingested drug is likely to persist in the stomach or upper small intestine).
    2. MDAC may be indicated to enhance elimination of some drugs if (1) more rapid elimination will benefit the patient and (2) more aggressive means of removal (eg, hemodialysis) are not immediately indicated or available. Considerations can include carbamazepine, dapsone, phenobarbital, quinine, theophylline, aspirin, or valproic acid.
    3. MDAC may also be useful as a gut decontamination measure when the quantity of drug or toxin ingested is greater than one-tenth of the usual charcoal dose (eg, an aspirin ingestion of >6-10 g) or when surface contact with the drug is hindered (eg, pharmacobezoars and wrapped or packaged drugs).
  3. Contraindications
    1. Patients at risk for gastrointestinal perforation or hemorrhage (recent surgery).
    2. Acid or alkali ingestions, unless other drugs have also been ingested (charcoal makes endoscopic evaluation more difficult).
    3. Charcoal-sorbitol mixtures should be avoided in children (risk for hypernatremia and dehydration from excessive sorbitol).
    4. Obtunded patients at risk for aspiration of charcoal (unless airway is protected).
    5. Gastrointestinal ileus or obstruction may prevent the administration of more than one or two doses.
  4. Adverse effects
    1. Pneumonitis and bronchiolitis obliterans have been reported after pulmonary aspiration of gastric contents containing activated charcoal.
    2. Constipation (may be prevented by coadministration of a cathartic, although this is not routinely advised).
    3. Diarrhea, dehydration, hypermagnesemia, and hypernatremia resulting from coadministered cathartics, or even after a single large dose of a premixed sorbitol-containing charcoal product.
    4. Intestinal bezoar with obstruction (in particular, with multiple doses given to patients who have impaired bowel motility).
    5. Corneal abrasions have occurred when activated charcoal was spilled in the eyes.
    6. Use in pregnancy. Activated charcoal is not systemically absorbed. Diarrhea resulting in shock or hypernatremia in the mother could conceivably affect the fetus adversely.
  5. Drug or laboratory interactions
    1. Activated charcoal may reduce, prevent, or delay the absorption of orally administered antidotes or other drugs (eg, acetylcysteine).
    2. The adsorptive capacity of activated charcoal may be diminished by the concurrent ingestion of ice cream, milk, or sugar syrup; the clinical significance is unknown but is probably minor.
    3. MDAC may enhance the elimination of some necessary therapeutic drugs (eg, anticonvulsants).
  6. Dosage and method of administration
    1. Initial dose
      1. Administer activated charcoal, 1 g/kg (adult dose: 50-100 g; child younger than 5 years: 0.5-1 g/kg or 10-25 g) orally or via gastric tube, or if the quantity of toxin ingested is known, at least 10 times the amount of ingested toxin by weight. For massive overdoses (eg, 60-100 g of aspirin), this may need to be given in divided doses over 1-2 days.
      2. Palatability may be improved by mixing with flavored drinks (cola) and, for children, placing in an opaque, covered cup and having them use a straw.
      3. The airway should be protected in obtunded patients to help prevent aspiration.
    2. Multiple-dose charcoal (MDAC)
      1. Administer activated charcoal, 15-30 g (0.25-0.5 g/kg) every 2-4 hours or hourly (adults: average rate of 12.5 g/h; children: rate of 0.2 g/kg/h) orally or by gastric tube. (The optimal regimen and dose are unknown, but more frequent dosing or continuous gastric infusion may be advantageous.) Whole-bowel irrigation may help move the charcoal through the intestinal tract.
      2. End points for repeat-dose charcoal therapy include clinical improvement and declining serum drug level; the usual empiric duration is 24-48 hours.
    3. For patients with nausea or vomiting, administer antiemetics (metoclopramide or ondansetron) and consider giving the charcoal by gastric tube.