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  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. Repeated oral doses of activated charcoal 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. Co-administration with cathartics is of unproven benefit and is associated with risks (see Cathartics).

  2. Indications

    1. Activated charcoal is often used orally after an ingestion to limit drug or toxin absorption. It is most effective if given within 1 hour of an ingestion, and effectiveness is subject to numerous variables (eg, charcoal-to-substance ratio, contact time, pH, substance solubility, and whether ingested drug is likely to persist in the stomach or upper small intestine). However, evidence for benefit in the clinical setting is limited.

    2. Repeated doses of activated charcoal 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 (See Repeat-dose activated charcoal).

    3. Repeated doses of activated charcoal may be useful 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. Gastrointestinal ileus or obstruction may prevent the administration of more than one or two doses. Patients at risk for gastrointestinal perforation or hemorrhage (recent surgery) should not receive activated charcoal.

    2. Acid or alkali ingestions, unless other drugs have also been ingested (charcoal makes endoscopic evaluation more difficult).

    3. Use of 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).

  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 co-administration of a cathartic, although this is not routinely advised).

    3. Diarrhea, dehydration, hypermagnesemia, and hypernatremia resulting from co-administered cathartics, especially with repeated doses of charcoal and 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 ...

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