プラリドキシム塩化物
Pralidoxime Chloride
2-Formyl-1-methylpyridinium chloride oxime
別名: Protopam Chloride · 2-Formyl-1-methylpyridinium chloride oxime · 2-PAM chloride · 2-PAMCl · 2-pyridine aldoxime methochloride
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 |
|---|---|---|---|---|---|
| Organophosphate poisoning | 20 mg/kg | IM or slow IV | 2-3 times a day | — | 🌎 NA |
| Organophosphate poisoning | 10-15 mg/kg | IM or SC | q8-12h | 36 hour minimum | 🌎 NA |
| Organophosphate poisoning | 50 mg/kg | slow IV | May repeat in one hour if severe | Recovery should occur gradually over 48 hours | 🌎 NA |
| Organophosphate poisoning | 50 mg/kg | IV | Repeat in one hour if signs persist, then q8h | 24-48 hours | 🌎 NA |
- Organophosphate poisoning: Works best when combined with atropine. Initial dose IM or slow IV; subsequent doses IM or SC.
- Organophosphate poisoning: Give atropine first (0.1 mg/kg IV, then 0.3 mg/kg IM). Dilute pralidoxime in 10% glucose. For small dogs, may administer IM or IP. Reduce dose in renal failure.
- Organophosphate poisoning: Give slowly or with fluids over a 30-minute period. If clinical signs intensify (e.g., respiratory depression), reduce dose and give as repeated one-hour infusions every 4-8 hours in combination with atropine.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Organophosphate poisoning | 20 mg/kg | IM or slow IV | 2-3 times a day | — | 🌎 NA |
| Organophosphate poisoning | 10-15 mg/kg | IM or SC | q8-12h | 36 hour minimum | 🌎 NA |
| Organophosphate poisoning | 50 mg/kg | slow IV | May repeat in one hour if severe | Recovery should occur gradually over 48 hours | 🌎 NA |
| Organophosphate poisoning | 20 mg/kg | IV | Repeat in one hour if signs persist, then q8h | 24-48 hours | 🌎 NA |
| Organophosphate poisoning | 20 mg/kg | IM or IV | May repeat q6-8h | — | 🌎 NA |
- Organophosphate poisoning: Works best when combined with atropine. Initial dose IM or slow IV; subsequent doses IM or SC.
- Organophosphate poisoning: Give atropine first. Dilute in 10% glucose. May administer IM or IP. Reduce dose in renal failure.
- Organophosphate poisoning: Give slowly or with fluids over a 30-minute period.
- Organophosphate poisoning: Give within first 24 hours of exposure. Combine with atropine or give separately. Do not use in carbamate toxicity.
鳥
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Organophosphate poisoning | 10-20 mg/kg | Not specified | q8-12h | — | 🌎 NA |
| Organophosphate poisoning | 10-100 mg/kg | IM | q24-48h or repeat once in 6 hours | — | 🌎 NA |
- Organophosphate poisoning: Give with atropine (0.2-0.5 mg/kg IM q3-4h).
馬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Organophosphate poisoning | 20 mg/kg (may require up to 35 mg/kg) | IV | q4-6h | — | 🌎 NA |
牛
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Organophosphate poisoning | 30 mg/kg | IM | q8h | — | 🌎 NA |
| Organophosphate poisoning | 25-50 mg/kg | IV | Single dose, or maximum of 100 mg/kg/day as an IV drip | — | 🌎 NA |
- Organophosphate poisoning: FARAD recommends a 28-day meat and a 6-day milk withdrawal time.
- Organophosphate poisoning: Give as a 20% solution over 6 minutes.
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
プラリドキシム（通称 2-PAM）は、獣医学において主に有機リン（OP）中毒の治療に使用される特異的な解毒剤です。有機リンは、古い殺虫剤、農薬、一部の神経剤に一般的に含まれています。これらはアセチルコリンエステラーゼ（AChE）に不可逆的に結合して阻害し、神経シナプスや神経筋接合部でのアセチルコリンの大量蓄積を引き起こします。
プラリドキシムはコリンエステラーゼ再賦活薬として働き、結合が永久的になる（「エイジング」と呼ばれるプロセス）前に、酵素から有機リン分子を効果的に引き離します。
臨床上のポイント: プラリドキシムはほぼ常にアトロピンと併用されます。アトロピンはアセチルコリン過剰によるムスカリン作用（SLUDDE症状：流涎、流涙、排尿、排便、呼吸困難、嘔吐）をブロックしますが、プラリドキシムはニコチン作用（特に重度の筋振戦、筋力低下、呼吸筋を含む麻痺）を軽減するために必要です。カルバメート中毒に対しては、カルバメートとAChEの結合がオキシム系再賦活薬を必要とせずに自然に可逆的となるため、一般的に推奨されません。
作用機序
Pralidoxime works by directly reactivating the acetylcholinesterase enzyme that has been inhibited by organophosphates.
- Organophosphates bind to the esteratic site of acetylcholinesterase (AChE) via phosphorylation, inactivating the enzyme.
- Accumulation of acetylcholine (ACh) occurs at muscarinic and nicotinic receptors → severe overstimulation.
- Pralidoxime possesses a high affinity for the AChE enzyme.
- Via nucleophilic attack, the oxime group of pralidoxime binds to the offending phosphoryl group of the organophosphate.
- The pralidoxime-organophosphate complex breaks away from the enzyme → AChE is reactivated and resumes breaking down ACh.
Important Mechanistic Note: If the phosphorylated enzyme undergoes a chemical change (loss of an alkyl group) before pralidoxime is administered, the bond becomes permanent. This is known as "aging". Therefore, pralidoxime is most effective when given within 24 hours of exposure, though some benefit may be seen up to 36-48 hours in massive exposures.
安全性・警告
禁忌
- Hypersensitivity to pralidoxime
- Carbamate poisoning (generally not recommended as inhibition is rapidly reversible)
有害事象
- Tachycardia (especially with rapid IV injection)
- Muscle rigidity
- Transient neuromuscular blockade
- Laryngospasm
注意事項
Use with caution in patients receiving anticholinesterase agents for the treatment of myasthenia gravis, as it may precipitate a myasthenic crisis. Use cautiously and at a reduced dosage rate in patients with renal impairment. Must generally be given within 24 hours of exposure to be effective. Rapid IV injection should be avoided to prevent tachycardia, muscle rigidity, and laryngospasm.
医薬品相互作用
Anticholinesterases can potentiate the action of barbiturates; use with caution.
Use should be avoided in patients with organophosphate toxicity.
Use should be avoided in patients with organophosphate toxicity.
Use should be avoided in patients with organophosphate toxicity.
Use should be avoided in patients with organophosphate toxicity.
Use should be avoided in patients with organophosphate toxicity.
監視
- Clinical signs associated with organophosphate poisoning (SLUDDE signs, muscle fasciculations, weakness)
- Heart rate and rhythm (especially during IV administration)
- Respiratory rate and effort
薬物動態
吸収
Marginally absorbed after oral dosing; oral dosage forms are no longer available in the United States.
分布
Distributed primarily throughout the extracellular water. Because of its quaternary ammonium structure, it is historically not believed to enter the CNS in significant quantities, but recent studies and clinical responses have led some to question this belief.
代謝
Thought to be metabolized by the liver.
消失
Excreted as both metabolite(s) and unchanged drug in the urine.
過剰投与
The acute LD50 of pralidoxime in dogs is 190 mg/kg. At high dosages, it causes signs associated with its own anticholinesterase activity.
Clinical signs of toxicity in dogs may be exhibited as:
- Muscle weakness
- Ataxia
- Vomiting
- Hyperventilation
- Seizures
- Respiratory arrest
- Death
製品
製剤
- Powder for injection
ヒト用医薬品
- Pralidoxime Chloride Powder for Injection: 1 gram in 20 mL single-use vials (Protopam Chloride)
規制ステータス
規制データなし: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Unless otherwise instructed by the manufacturer, pralidoxime chloride powder for injection should be stored at room temperature. After reconstituting with sterile water for injection, the solution should be used within a few hours. Do not use sterile water with preservatives added.
飼主向け情報
- 緊急治療: この薬は、特定の種類の農薬や神経剤（有機リン）中毒に対する極めて重要な救命解毒剤です。
- 入院が必要: この薬の投与中は、ペットを入院させ、獣医療専門家による厳密な監視を受ける必要があります。
- 時間との勝負: この解毒剤は、曝露後できるだけ早く（理想的には最初の24時間以内に）投与した場合に最も効果的です。
- 併用療法: 重度の中毒症状を完全にコントロールするために、ほぼ常にアトロピンと呼ばれる別の解毒剤と一緒に投与されます。
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