Activated charcoal
Formal Definition
A finely powdered carbon preparation with high surface area that adsorbs many toxic substances in the GI tract, reducing absorption into the systemic circulation; most effective within 1–2 hours of ingestion, given orally or via nasogastric tube; does NOT bind alcohols, metals, caustics, or lithium.
How It's Used on the Ward
"Give activated charcoal" or "AC" — the black slurry given early in many overdoses to bind the drug before it absorbs.
Example
""Intentional ingestion of unknown quantity of quetiapine 45 minutes ago, patient awake and cooperative with intact gag reflex: 50g activated charcoal PO now. If she becomes obtunded, secure the airway before any further GI decontamination.""
Clinical Context
Dose: 1 g/kg (adult: 50g) in water or sorbitol suspension. Adsorbs: most pharmaceuticals, many plant toxins, organophosphates. Does NOT adsorb: alcohols (ethanol, methanol, ethylene glycol), lithium, iron, potassium, caustics, hydrocarbons. Contraindications: unprotected airway (aspiration risk), caustic ingestion, bowel obstruction. Best within 60 minutes of ingestion; evidence limited beyond 2 hours. Multi-dose activated charcoal (MDAC) for some drugs (ASA, carbamazepine, theophylline) to interrupt enterohepatic circulation. Do not give if obtunded or intubation is likely without securing airway first.
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