戊巴比妥鈉
Pentobarbital Sodium
Pentobarbital sodium
別名: Nembutal · Pentobarbitone sodium
由 VetSheet 獸醫團隊審訂更新於 2026年4月5日本內容以實證獸醫文獻為本
各物種劑量
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概覽
戊巴比妥鈉是一種短效巴比妥類藥物，在獸醫學中歷史上被用作全身麻醉劑和鎮靜劑。由於更安全的吸入性麻醉劑和如丙泊酚（Propofol）等注射劑的出現，其治療用途現在主要限於控制難治性癲癇重積狀態（例如繼發於番木鱉鹼或破傷風毒素中毒）以及作為安樂死溶液的主要成分。
- 中樞神經系統抑制： 能夠引起所有程度的中樞神經系統改變，從輕度鎮靜到深度昏迷和死亡。
- 心血管與呼吸系統影響： 引起劑量依賴性的呼吸抑制和心血管改變（心搏過速、心肌收縮力下降和低血壓）。
臨床要點： 戊巴比妥的治療指數狹窄，且不具備內在鎮痛作用。它屬於 DEA 附表 II 管制藥物（當未配製為安樂死組合產品時）。
作用機制
Pentobarbital acts as a profound CNS depressant through multiple mechanisms:
- GABA-A Receptor Modulation: Binds to the barbiturate site on the GABA-A receptor, prolonging the duration of chloride channel opening → hyperpolarization of the postsynaptic membrane → profound CNS inhibition. At high doses, it is directly GABA-mimetic.
- Glutamate Inhibition: Inhibits excitatory neurotransmission by blocking glutamate release and AMPA/kainate receptors.
- Neurotransmitter Release: Inhibits the release of acetylcholine and norepinephrine.
- Calcium Channels: At high anesthetic doses, it inhibits calcium uptake at nerve terminals.
安全性與警告
禁忌症
- Known hypersensitivity to barbiturates
- Severe liver disease
- Nephritis
- Severe respiratory depression
- Lidocaine-induced seizures
- Pregnancy (Category D - embryotoxic/teratogenic)
不良反應
- Respiratory depression (can be severe)
- Hypothermia
- Paradoxical excitement during recovery (especially in dogs)
- Cardiovascular depression (decreased contractility, hypotension)
- Severe tissue irritation and necrosis (if given perivascularly or SC)
注意事項
Administer IV SLOWLY (unless used for euthanasia). Very irritating if given SC or perivascularly; do NOT give intra-arterially (IA). Use cautiously in patients who are hypovolemic, anemic, or have borderline hypoadrenal, cardiac, or respiratory disease. Cats (especially females) are particularly sensitive to respiratory depressant effects. Use with caution in neonates due to higher CNS penetration.
藥物相互作用
Increased risk for hepatotoxicity, particularly with large or chronic barbiturate doses.
Fatalities reported when treating lidocaine-induced seizures with pentobarbital; use diazepam instead.
Barbiturates may affect phenytoin metabolism and vice versa; blood level monitoring indicated.
May induce enzymes that increase the metabolism of barbiturates.
May increase the CNS depressant effect of pentobarbital.
May increase the CNS depressant effect of pentobarbital.
May increase the CNS depressant effect of pentobarbital.
May increase the CNS depressant effect of pentobarbital.
監測
- Respiratory rate, depth, and effort (ventilatory support must be available)
- Heart rate and rhythm
- Blood pressure
- Body temperature (monitor for hypothermia)
- Depth of anesthesia/sedation
藥物動力學
半衰期
吸收
Rapidly absorbed from the gut after oral or rectal administration. Peak plasma concentrations occur 30-60 minutes post-oral dosing. Onset of action is 15-60 minutes (PO) and <1 minute (IV).
分佈
Distributes rapidly to all body tissues, with highest concentrations in the liver and brain. 35-45% bound to plasma proteins. Highly lipid-soluble; patient fat content alters distribution. Crosses the placenta and enters milk. Neonatal CNS levels can be up to 6 times higher than adults.
代謝
Metabolized in the liver principally by oxidation. Induces hepatic microsomal enzymes with extended use. Ruminants (sheep/goats) metabolize it very rapidly.
排除
Excreted via the kidneys. Excretion is not appreciably enhanced by increased urine flow or alkalinizing the urine.
過量
In dogs, the reported oral LD50 is 85 mg/kg and IV LD50 is 40-60 mg/kg. Fatalities from ingestion of meat from animals euthanized by pentobarbital have been reported in dogs.
Treatment:
- Removal of ingested product from the gut if appropriate (e.g., gastric lavage, activated charcoal).
- Provide aggressive respiratory (ventilatory) and cardiovascular support.
- Forced alkaline diuresis is of little benefit.
- Peritoneal dialysis or hemodialysis may be beneficial in severe intoxications.
可用產品
劑型
- Injection
- Oral solution
獸醫用
- Nembutal® (Historical)
- Various Euthanasia Solutions (Combination products)
人用標示
- Nembutal® Sodium Injection
各地核准狀態
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儲存與穩定性
Store at controlled room temperature. Protect from excessive heat and freezing.
飼主須知
寵物主人重要須知：
- 麻醉後護理： 當藥效消退時，您的寵物可能會經歷一段不安的恢復期（如發聲、划水動作或興奮）。請將牠們安置在安靜、光線昏暗且安全的環境中，以防受傷。
- 體溫控制： 戊巴比妥會降低體溫。請保持寵物溫暖舒適，但避免使用電熱毯等直接熱源，以免造成燙傷。
- 哺乳期寵物： 此藥物會分泌至母乳中，可能導致哺乳的新生幼崽嗜睡。
- 毒性警告： 絕對不可讓寵物撿食或食用已被安樂死動物的遺體。戊巴比妥會殘留在組織中，若被誤食會導致致命中毒。
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