アセチルシステイン
Acetylcysteine
N-acetyl-L-cysteine
別名: Mucomyst · Acetadote · NAC · ACC · Ilube · Parvolex · Fluimucil · N-acetylcysteine · N-acetyl-L-cysteine · 5052 acetylcysteinum · NSC-111180
VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス
用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。
動物種別用量
🌎 NA — North America🌍 EU — Europe
犬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Acetaminophen toxicity | 140 mg/kg PO loading dose, followed by 70 mg/kg PO q6h | PO | q6h | For 7 treatments (up to 12-17 doses for massive ingestions) | 🌎 NA |
| Acetaminophen toxicity | 150 mg/kg PO or IV initially, then 50 mg/kg q4h | PO/IV | q4h | For 17 additional doses | 🌎 NA |
| Acetaminophen toxicity | 140 mg/kg PO loading dose, then 70 mg/kg PO every 6 hours | PO | q6h | For 7 treatments | 🌎 NA |
| Phenol toxicity | 140 mg/kg PO or IV initially, then 50 mg/kg q4h | PO/IV | q4h | For 3 days | 🌎 NA |
| Hepatotoxicity secondary to xylitol poisoning | 140-280 mg/kg loading dose IV or PO; followed by 70 mg/kg four times daily | IV/PO | q6h | — | 🌎 NA |
| Degenerative myelopathy (anecdotal) | 25 mg/kg PO q8h for 2 weeks, then q8h every other day | PO | q8h | Indefinitely (every other day after 2 weeks) | 🌎 NA |
| Mucolytic | nebulize 50 mg as a 2% (dilute with saline) solution over 30-60 min or instil directly into the trachea 1-2 ml of a 20% solution | Nebulization/Intratracheal | prn | As needed | 🌍 EU |
| Paracetamol poisoning | 140-280 mg/kg diluted to a 5% solution using 5% dextrose by slow i.v. infusion over 15-20 min, followed by further slow infusions of 70 mg/kg (similarly diluted) every 6 hours | IV | q6h | for at least 7 doses | 🌍 EU |
| KCS | 1 drop of the ophthalmic solution | topical | q6-8h | As directed | 🌍 EU |
- Acetaminophen toxicity: Dilute to 5% in dextrose or sterile water. May also be given slow IV over 15-20 minutes. Wait 2-3 hours after activated charcoal if giving PO.
- Phenol toxicity: May be partially effective to reduce hepatic and renal injury.
- Hepatotoxicity secondary to xylitol poisoning: Used as part of a comprehensive protocol including vitamin K, plasma, SAMe, vitamin E, and silymarin.
- Degenerative myelopathy (anecdotal): Dilute 20% solution to 5% with chicken broth. Used in conjunction with aminocaproic acid. Note: No treatment has been shown to be effective in published trials.
- Mucolytic: Dilute with saline for nebulization.
- Paracetamol poisoning: Administer after inducing emesis if appropriate (within 2 hours of ingestion). IV preferred for serious intoxications. Can be given PO but must be diluted to improve palatability.
- KCS: Rarely used now for this indication.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Acetaminophen toxicity | 140 mg/kg PO loading dose, followed by 70 mg/kg PO four times daily (q6h) | PO | q6h | For 7 treatments (up to 12-17 doses for massive ingestions) | 🌎 NA |
| Phenol toxicity | 140 mg/kg PO or IV initially, then 50 mg/kg q4h | PO/IV | q4h | For 3 days | 🌎 NA |
| Adjunctive treatment of hepatic lipidosis | 140 mg/kg IV over 20 minutes, then 70 mg/kg IV q12h | IV | q12h | — | 🌎 NA |
| Mucolytic | nebulize 50 mg as a 2% (dilute with saline) solution over 30-60 min or instil directly into the trachea 1-2 ml of a 20% solution | Nebulization/Intratracheal | prn | As needed | 🌍 EU |
| Paracetamol poisoning | 140-280 mg/kg diluted to a 5% solution using 5% dextrose by slow i.v. infusion over 15-20 min, followed by further slow infusions of 70 mg/kg (similarly diluted) every 6 hours | IV | q6h | for at least 7 doses | 🌍 EU |
| KCS | 1 drop of the ophthalmic solution | topical | q6-8h | As directed | 🌍 EU |
- Acetaminophen toxicity: Dilute to 5% in dextrose or sterile water. May also be given slow IV over 15-20 minutes. Wait 2-3 hours after activated charcoal if giving PO.
- Phenol toxicity: May be partially effective to reduce hepatic and renal injury.
- Adjunctive treatment of hepatic lipidosis: Dilute 10% NAC with saline 1:4 and administer IV using a 0.25 micron filter.
- Mucolytic: Dilute with saline for nebulization.
- Paracetamol poisoning: IV administration is strongly preferred in cats as bioavailability is reduced with oral administration.
- KCS: Rarely used now for this indication.
馬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| To help break up chondroids in the guttural pouch | Instill 20% solution | Local instillation | — | — | 🌎 NA |
| Meconium impaction in neonatal foals | 8 grams in 20 g sodium bicarbonate in 200 mL water (pH of 7.6), give as enema as needed to effect | Enema | PRN | — | 🌎 NA |
| Meconium impaction in neonatal foals | Infuse slowly 100-200 mL of 4% acetylcysteine solution and retain for 30-45 minutes | Retention enema | Once | Retain 30-45 minutes | 🌎 NA |
- Meconium impaction in neonatal foals: Use a 30 French Foley catheter with a 30 cc bulb. Monitor for possible bladder distention.
用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。
概要
アセチルシステイン（NACとも呼ばれる）は、獣医学において非常に多用途な治療薬です。特に犬や猫におけるアセトアミノフェン（パラセタモール）中毒の救命解毒剤として最もよく知られており、重篤な肝壊死やメトヘモグロビン血症を防ぎます。
解毒作用に加えて、アセチルシステインは強力な粘液溶解剤でもあります。気道に投与されると、ドロドロとした粘液を効果的に分解し、気道分泌物の排出を助けます。
臨床応用：
- 毒物学： アセトアミノフェン、キシリトール、フェノール中毒の主な治療。
- 呼吸器系： ネブライザーまたは気管内注入により、慢性上部呼吸器疾患や粘液過多の状態を治療。
- 眼科： コラゲナーゼを阻害し、「融解性」角膜潰瘍の進行を止めるために局所塗布。
- 馬の医学： 喉嚢内の軟骨様物質を溶解するための局所使用、および新生仔馬の難治性胎便停滞に対する浣腸として使用。
- 内科： 猫の肝リピドーシスの補助治療、および犬の変性性脊髄症に対する経験的治療。
作用機序
Antidote Mechanism (Hepatoprotection): Acetaminophen is metabolized in the liver to a highly reactive and toxic intermediate called NAPQI (N-acetyl-p-benzoquinone imine). Normally, NAPQI is safely conjugated by endogenous glutathione. In an overdose, glutathione is rapidly depleted, allowing NAPQI to cause severe oxidative stress and hepatocellular necrosis. Acetylcysteine acts as a glutathione precursor and provides an alternate sulfhydryl substrate to conjugate directly with NAPQI, thereby neutralizing the toxin and restoring cellular antioxidant defenses.
Mucolytic Mechanism: The free sulfhydryl group (-SH) on the acetylcysteine molecule directly interacts with mucoproteins in respiratory secretions. It cleaves the disulfide bonds linking these proteins, which drastically reduces the viscosity of both purulent and non-purulent mucus. This effect is optimal in an alkaline environment (pH 7-9). It has no effect on living tissue or fibrin.
安全性・警告
禁忌
- Hypersensitivity to the drug (specifically for pulmonary indications)
有害事象
- Nausea and vomiting (especially with oral administration due to poor palatability)
- Urticaria (rare)
- Bronchospasm, chest tightness, and bronchial/tracheal irritation (when inhaled)
- Blood pressure changes and allergic reactions (reported with IV boluses in humans)
注意事項
Use with caution in animals with pre-existing bronchospastic diseases (e.g., feline asthma) when administering via the pulmonary route, as it may trigger bronchospasm. Oral administration can be challenging due to the extremely foul taste and odor (sulfur/rotten eggs); administration via a gastric or duodenal tube is often necessary. If using the inhalation solution for intravenous administration, it is highly recommended to use a 0.2-micron in-line filter. Use caution in nursing dams as it is unknown if the drug enters milk.
医薬品相互作用
May adsorb orally administered acetylcysteine, potentially reducing its systemic absorption and efficacy. A 2-3 hour wait between charcoal and oral acetylcysteine is recommended, or acetylcysteine should be given intravenously.
監視
- Hepatic enzymes (especially in dogs)
- Acetaminophen levels (if available)
- Hemogram, specifically monitoring methemoglobin values (especially critical in cats)
- Serum electrolytes
- Hydration status
薬物動態
吸収
Well absorbed from the gastrointestinal tract when administered orally.
分布
When administered via nebulization or intratracheally, most of the drug remains localized in the pulmonary tract to participate in sulfhydryl-disulfide reactions; the remainder is systemically absorbed.
代謝
Absorbed drug is rapidly deacetylated into the amino acid cysteine in the liver, which is then further metabolized.
過剰投与
Acetylcysteine is considered quite safe in overdose situations. The LD50 in dogs is reported to be 1 g/kg orally and 700 mg/kg intravenously. Massive overdoses may result in gastrointestinal distress (nausea, vomiting) or hypersensitivity reactions, but life-threatening toxicity from the drug itself is rare.
製品
製剤
- Injection: 20% (200 mg/mL)
- Oral/Inhalation Solution: 10% and 20%
- Oral capsules: 600 mg (OTC nutritional supplement)
ヒト用医薬品
- Acetylcysteine injection: 20% (200 mg/mL) in 30 mL single-dose vials (Acetadote)
- Acetylcysteine Oral Solution: 10% & 20% (Mucomyst)
- Acetylcysteine Inhalation Solution: 10% & 20% (Mucomyst)
- N-Acetylcysteine (NAC) 600 mg capsules (OTC nutritional supplement)
規制ステータス
Human authorized products used under the cascade.
Human authorized products used under the cascade.
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Unopened vials should be stored at room temperature (15-30°C). Once opened, vials must be refrigerated and used within 96 hours (products labeled specifically for IV use should be used within 24 hours). Acetylcysteine is incompatible with oxidizing agents and can liberate hydrogen sulfide when exposed to rubber, copper, or iron. It is incompatible in solution with amphotericin B, ampicillin, erythromycin, tetracyclines, hydrogen peroxide, and trypsin.
飼主向け情報
緊急時のみ使用： アセチルシステインは通常、生命を脅かす中毒（タイレノール/アセトアミノフェン誤飲など）を治療するために、獣医師の監督下で緊急時に使用されます。
- 味と匂い： 経口液体製剤は、腐った卵（硫黄）のような非常に強くて不快な匂いがし、味も非常に悪いです。ペットは服用を嫌がる可能性が高いです。病院では、全量を確実に投与するために、栄養チューブを介して投与されるか、強い風味のフレーバーと混ぜて与えられることがよくあります。
- 副作用： 最も一般的な副作用は吐き気や嘔吐です。経口投与後すぐにペットが嘔吐した場合は、再投与が必要になる可能性があるため、すぐに獣医師に連絡してください。
- モニタリング： 肝臓が回復し、毒素が体から排出されていることを確認するために、頻繁な血液検査を含む綿密なモニタリングが必要になります。
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