ペントバルビタール
Pentobarbital
Pentobarbital sodium
別名: Nembutal · Dolethal · Euthanimal · Euthasal · Euthatal · Euthoxin · Lethobarb · Pentoject · aethaminalum · mebubarbital · mebumal · pentobarbitalum · pentobarbitone · Pentobarbital sodium
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
監査済み v13 用量エビデンス
確認済み・計算対象外のエビデンス確認済み・計算対象外のエビデンス (4)
エビデンス表示のみ（自動計算対象外）
Crocodilians
TABLE 127.5. Agent: Pentobarbital. Dosage: 7.5–15 mg/kg ICe, or 8 mg/kg IM18,229. Species/Comments: Crocodilians.
エビデンス表示のみ（自動計算対象外）
Snakes/induction, 30–60 min; duration, ≥ 2 hr; prolonged recovery (risk of occasional fatalities); venomous snakes require twice as much as nonvenomous snakes;18 avoid use in lizards
TABLE 127.5. Agent: Pentobarbital. Dosage: 15–30 mg/kg ICe229. Species/Comments: Snakes/induction, 30–60 min; duration, ≥ 2 hr; prolonged recovery (risk of occasional fatalities); venomous snakes require twice as much as nonvenomous snakes;18 avoid use in lizards.
エビデンス表示のみ（自動計算対象外）
Chelonians
TABLE 127.5. Agent: Pentobarbital. Dosage: 10–18 mg/kg ICe229. Species/Comments: Chelonians.
エビデンス表示のみ（自動計算対象外）
Rarely used as an anesthetic agent in reptiles
TABLE 127.5. Agent: Pentobarbital. Dosage: —. Species/Comments: Rarely used as an anesthetic agent in reptiles.
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
ペントバルビタールは、獣医学において主に全身麻酔、化学的保定、および難治性てんかん重積状態の管理に使用される短時間作用型のオキシバルビツール酸系薬物です。
歴史的には全身麻酔薬として普及していましたが、治療域が狭く、強力な心肺抑制作用があるため、現在ではより安全で用量調整が容易な薬剤（プロポフォールやアルファキサロンなど）に大部分が取って代わられています。
臨床のポイント:
- てんかん重積状態: 難治性てんかん患者を「バルビツール酸昏睡」に導入するためによく使用されます。ただし、標準用量では真の抗てんかん作用は乏しく、全身麻酔薬として機能します。発作の身体的症状は止めますが、脳内の潜在的な発作活動を停止させない可能性があります。
- 呼吸管理: ペントバルビタールで治療を受ける患者は、強力な呼吸抑制のため、通常、人工呼吸器と集中治療室でのモニタリングが必要です。
- 安楽死: 非常に高用量では、ほとんどの獣医用安楽死液の主成分となります。
- 酵素誘導: 長期使用は肝臓のシトクロムP450酵素を強力に誘導し、併用薬の代謝を促進します。
作用機序
Pentobarbital exerts its profound central nervous system (CNS) depressant effects by interacting with the inhibitory neurotransmitter system.
- GABA_A Receptor Modulation: Binds to the barbiturate site on the GABA_A receptor → increases the duration of chloride channel opening → enhances chloride influx → hyperpolarization of the postsynaptic neuronal membrane.
- Glutamate Inhibition: At higher anesthetic doses, it also depresses the actions of the excitatory neurotransmitter glutamate via AMPA receptors.
- Result: Dose-dependent CNS depression ranging from mild sedation to general anesthesia, coma, and fatal respiratory depression.
安全性・警告
禁忌
- Severe hepatic impairment
- Severe respiratory depression or airway obstruction
- Porphyria
- Hypovolemia or severe cardiovascular instability (relative contraindication)
- Intramuscular (IM) administration (painful and slow to act)
- Use of euthanasia-specific solutions for seizure control or anesthesia
有害事象
- Profound respiratory depression (apnea)
- Depression of myocardial metabolism
- Vasodilation and decreased venous return
- Hypotension and decreased cardiac perfusion
- Poikilothermia (hypothermia)
- Decreased urinary output
- Seizure-like movements or excitement during recovery from anesthesia
- Excitement and injury during induction/recovery in large animals (especially horses)
- Narcotic excitement (if not premedicated)
- Agonal gasping (reflexive, not a sign of pain)
- Muscle twitching
- Vocalization (rare, usually associated with excitement phase)
注意事項
Cardiopulmonary Depression: Pentobarbital causes dose-dependent respiratory and cardiovascular depression. Patients in a 'barbiturate coma' commonly require mechanical ventilation and intensive care support (e.g., saline infusion and dopamine to manage hypotension).
Individual Variation: There is tremendous individual variation in response when used at standard safe doses. Always titrate to effect.
Laboratory Interference: Barbiturates may cause increased retention of bromosulfophthalein (BSP) and give falsely elevated results. Do not administer within 24 hours before BSP retention tests.
- Equine Use: Generally not considered an ideal agent for adult horses due to the possible development of excitement and injury when the animal is 'knocked down'.
- Tissue Irritation: Highly alkaline (pH 9-10.5); perivascular injection can cause severe tissue necrosis.
医薬品相互作用
Decreased effect by lowering serum concentration (due to hepatic enzyme induction)
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect (may persist for weeks after barbiturate is discontinued)
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Decreased effect by lowering serum concentration
Increase the CNS depressant effect of pentobarbital
Increase the CNS depressant effect of pentobarbital
監視
- Levels of consciousness and/or seizure control
- Respiratory rate, rhythm, and depth (capnography and pulse oximetry highly recommended)
- Cardiac signs (heart rate, blood pressure, ECG)
- Body temperature (monitor for poikilothermia)
- Routine blood counts and liver function tests (if used chronically)
- Absence of heartbeat (auscultation)
- Absence of respiration
- Loss of corneal reflex
- Pupillary dilation
薬物動態
半減期
吸収
Rapidly absorbed following oral or intraperitoneal administration.
分布
Highly lipid soluble; rapidly crosses the blood-brain barrier to exert CNS effects. It subsequently redistributes from the brain to highly perfused tissues, and eventually to muscle and fat, which terminates its initial anesthetic effect.
代謝
Extensively metabolized in the liver via cytochrome P450 enzymes. Chronic administration induces these enzymes, accelerating its own metabolism and that of other drugs.
消失
Metabolites are primarily excreted by the kidneys.
過剰投与
Overdose of pentobarbital leads to profound central nervous system depression, progressing rapidly to coma, severe respiratory depression (apnea), cardiovascular collapse, and death.
- Treatment: There is no specific reversal agent for barbiturates. Treatment is entirely supportive.
- Interventions: Immediate intubation and mechanical ventilation are required. Intravenous fluids and vasopressors (e.g., dopamine) should be administered to support blood pressure and cardiac output. Maintain body temperature to prevent severe hypothermia.
製品
製剤
- Injection (50 mg/mL)
- Suppositories
- Injectable: 200 mg/ml non-sterile aqueous solution
- Injectable: 400 mg/ml non-sterile aqueous solution
- Injectable: 500 mg/ml non-sterile aqueous solution
動物用医薬品
- Dolethal 200 mg/ml solution for injection
- Euthanimal 200 mg/ml / 400 mg/ml solution for injection
- Euthasal 400 mg/ml solution for injection
- Euthatal 200 mg/ml solution for injection
- Euthoxin 500 mg/ml solution for injection
- Lethobarb 200 mg/ml solution for injection
- Pentoject 200 mg/ml solution for injection
ヒト用医薬品
- Pentobarbital Sodium Injection: 50 mg/mL in 2 mL Tubex; generic; (WyethAyerst); (Rx, C-II)
規制ステータス
Carcasses must not enter the food chain.
POM-V CD SCHEDULE 3. Safe custody requirements apply.
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
The injectable product should be stored at room temperature; suppositories should be kept refrigerated. The aqueous solution is not very stable and should not be used if it contains a precipitate. Because precipitates may occur, pentobarbital sodium should not be added to acidic solutions.
飼主向け情報
この薬は強力な鎮静薬および麻酔薬です。
- 院内での使用: ほぼ例外なく、動物病院内で専門家の厳密な監督の下、多くの場合集中治療室で使用されます。
- 自宅での使用: 自宅用に経口薬が処方された場合、獣医師の用量指示を厳格に守ることが極めて重要です。過剰投与は致命的となる可能性があります。
- 安全性: この薬は安全で子供が開けにくい容器に保管し、子供や他のペットの手の届かない場所に完全に隔離してください。厳格に管理されている規制薬物です。
VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。