Activated Charcoal
Activated charcoal is a highly porous, fine black powder used as a **gastrointestinal adsorbent** in the emergency management of certain toxicities and drug overdoses. * **Clinical Pearl**: It acts as a broad-spectrum adsorbent for many organic compounds, though its efficacy depends heavily on the timing of administration (ideally within 1-2 hours of ingestion) and the specific properties of the toxin. * It is **not effective** for small, highly polar, or water-soluble compounds such as mineral acids, caustic alkalis, alcohols (ethanol, methanol), ferrous sulfate, lithium, nitrates, sodium chloride/chlorate, or petroleum distillates. * Slurries or suspensions are generally more effective than compressed tablets due to a larger available surface area.
Mechanism: Activated charcoal possesses an extremely large surface area. It binds to toxins in the upper GI tract via **ion-ion interactions**, **hydrogen bonding**, **dipole forces**, and **Van der Waals forces**. * **Mechanism**: Toxin binds to charcoal in the gut lumen โ forms a stable charcoal-toxin complex โ prevents systemic absorption โ complex is excreted safely in the feces. * **Enterohepatic Recirculation**: For drugs that undergo enterohepatic recycling, repeated doses of activated charcoal can act as a "gut dialyzer," pulling systemic toxins back into the GI lumen to be trapped and excreted.
Dosing by species
- Plant intoxications ยท 1-5 g/kg ยท PO ยท Single or multiple doses ยท Mix with cathartic (e.g., sodium/magnesium sulfate 250-500 mg/kg or sorbitol 70% 3 ml/kg) if no diarrhea is present.
- Plant intoxications ยท 1-5 g/kg ยท PO ยท Single or multiple doses ยท Mix with cathartic (e.g., sodium/magnesium sulfate 250-500 mg/kg or sorbitol 70% 3 ml/kg) if no diarrhea is present.
- Gastrointestinal absorbent ยท 10 mL of a 20% slurry (1 g of charcoal in 5 mL of water) per kg ยท PO/Orogastric tube ยท Single dose
- Acute poisoning ยท 1-4 g/kg ยท PO/Nasogastric tube ยท q4-6h ยท As needed for toxins that are recirculated ยท After decontamination of the GI tract
- Acute poisoning ยท 1-4 g/kg in 50-200 mL of water ยท PO ยท Single or repeated doses ยท Concurrent with or within 30 minutes of giving charcoal, give an osmotic cathartic.
- Acute poisoning ยท 1-5 g/kg ยท PO ยท Single dose ยท Diluted in water at 1 g charcoal/5-10 mL water. Follow in 30 minutes with sodium sulfate oral cathartic.
- After toxin ingestion ยท 0.5-4 g/kg ยท PO ยท Repeat dosing as required if emesis or massive toxin ingestion occurs, or for highly lipid-soluble toxins ยท As needed ยท Administer as a slurry in water. General rule: administer at a dose of at least 10 times the volume of intoxicant ingested.
Routes of administration
Contraindications
- Ingestion of mineral acids or caustic alkalis (ineffective and may obscure endoscopic evaluation)
- Patients lacking a gag reflex or actively vomiting (unless airway is protected via intubation)
- GI obstruction or perforation
Adverse effects
- Emesis (especially with rapid administration)
- Aspiration pneumonia (if aspirated)
- Constipation or diarrhea
- Black feces
- Hypernatremia (especially in small dogs and cats)
- Loose stools and vomiting (associated with sorbitol-containing products)
Drug interactions
- Other orally administered therapeutic agents ยท Charcoal will adsorb other drugs; separate administration by at least 3 hours.
- Dairy products ยท May reduce the adsorptive capacity of activated charcoal.
- Mineral oil ยท May reduce the adsorptive capacity of activated charcoal.
- Polyethylene glycol / Electrolyte solutions (e.g., Go-Lytely) ยท May reduce the adsorptive capacity of activated charcoal.
- All orally administered drugs ยท Reduces the absorption and therefore efficacy of orally administered drugs ยท major
Monitoring
- Toxin/drug serum levels (if applicable)
- Clinical signs of the specific toxicity
- Serum sodium levels (especially if patient develops neurologic signs like tremors, ataxia, or seizures)
Overdose
Overdosage or overly rapid administration can cause severe electrolyte abnormalities, specifically **hypernatremia**, due to an osmotic effect pulling water into the GI tract. Treat with reduced sodium fluids (e.g., D5W, 0.45% NaCl) and warm water enemas to alleviate the condition.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.