活性炭
活性炭は非常に多孔質な黒色の微粉末であり、特定の毒物や薬物の過剰摂取の救急処置において**消化管吸着剤**として使用されます。 * **臨床のポイント**：多くの有機化合物に対する広域スペクトルの吸着剤として機能しますが、その有効性は投与のタイミング（理想的には摂取後1〜2時間以内）および毒物の特定の性質に大きく依存します。 * 鉱酸、苛性アルカリ、アルコール（エタノール、メタノール）、硫酸第一鉄、リチウム、硝酸塩、塩化ナトリウム/塩素酸塩、石油蒸留物などの低分子、高極性、または水溶性の化合物には**無効**です。 * 利用可能な表面積が大きいため、通常、スラリー（泥状）または懸濁液は圧縮錠剤よりも効果的です。
作用機序: 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 → forms a stable charcoal-toxin complex → prevents systemic absorption → 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.
動物種別の用量
- Plant intoxications · 1-5 g/kg · PO · Single or multiple doses · 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 · 1-5 g/kg · PO · Single or multiple doses · 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 · 10 mL of a 20% slurry (1 g of charcoal in 5 mL of water) per kg · PO/Orogastric tube · Single dose
- Acute poisoning · 1-4 g/kg · PO/Nasogastric tube · q4-6h · As needed for toxins that are recirculated · After decontamination of the GI tract
- Acute poisoning · 1-4 g/kg in 50-200 mL of water · PO · Single or repeated doses · Concurrent with or within 30 minutes of giving charcoal, give an osmotic cathartic.
- Acute poisoning · 1-5 g/kg · PO · Single dose · Diluted in water at 1 g charcoal/5-10 mL water. Follow in 30 minutes with sodium sulfate oral cathartic.
- After toxin ingestion · 0.5-4 g/kg · PO · Repeat dosing as required if emesis or massive toxin ingestion occurs, or for highly lipid-soluble toxins · As needed · Administer as a slurry in water. General rule: administer at a dose of at least 10 times the volume of intoxicant ingested.
投与経路
禁忌
- 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
有害事象
- 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)
薬物相互作用
- Other orally administered therapeutic agents · Charcoal will adsorb other drugs; separate administration by at least 3 hours.
- Dairy products · May reduce the adsorptive capacity of activated charcoal.
- Mineral oil · May reduce the adsorptive capacity of activated charcoal.
- Polyethylene glycol / Electrolyte solutions (e.g., Go-Lytely) · May reduce the adsorptive capacity of activated charcoal.
- All orally administered drugs · Reduces the absorption and therefore efficacy of orally administered drugs · major
モニタリング
- 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)
過量投与
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.
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