苯巴比妥
Phenobarbital
Phenobarbital sodium, phenylethylbarbituric acid, phenylethylmalonylurea
別名: Luminal Sodium · Solfoton · Epiphen · Epityl · Phenoleptil · Fenobarbital · Phenemalum · Phenobarbitalum · Phenobarbitone · Phenylethylbarbituric acid · Phenylethylmalonylurea · Phenobarbital 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
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
各物種劑量
🌎 NA — North America🌍 EU — Europe
狗
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Idiopathic epilepsy (initial dose) | 2-2.5 mg/kg | PO | q12h | — | 🌎 NA |
| Idiopathic epilepsy (initial maintenance) | 2.5-3 mg/kg | PO | q12h | — | 🌎 NA |
| Idiopathic epilepsy (rapid loading) | 16-20 mg/kg once IV loading dose, then 2-5 mg/kg PO q12h | IV/PO | Once then q12h | — | 🌎 NA |
| Status epilepticus | 2-5 mg/kg bolus (repeat at 20 min intervals up to 2x), or add to diazepam infusion at 2-10 mg/hour | IV | PRN | — | 🌎 NA |
| Status epilepticus (post-benzodiazepine) | 5-8 mg/kg | IV | q4-6h | — | 🌎 NA |
| Sialadenosis | 1 mg/kg | PO | q12h | 3 months | 🌎 NA |
| Sedation | 2.2-6.6 mg/kg | PO | q12h | — | 🌎 NA |
| Irritable bowel syndrome | 2.2 mg/kg | PO | q12h | — | 🌎 NA |
| Compulsive behaviors (adjunctive) | 2-20 mg/kg | PO | q12-24h | — | 🌎 NA |
- Idiopathic epilepsy (initial dose): Monitor serum concentrations 2-3 weeks after initiating. Target 20-35 mcg/mL.
- Idiopathic epilepsy (initial maintenance): Perform baseline CBC, chem, UA before starting.
- Status epilepticus: If seizures persist after diazepam therapy.
- Status epilepticus (post-benzodiazepine): Continue until seizures are under control.
- Sialadenosis: Slowly weaned off after 3 months.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Idiopathic epilepsy (initial dose) | 2-2.5 mg/kg | PO | q12h | — | 🌎 NA |
| Idiopathic epilepsy (maintenance) | 1-2 mg/kg | PO | q12h | — | 🌎 NA |
| Idiopathic epilepsy (rapid loading) | 16-20 mg/kg once IV loading dose, then 1-5 mg/kg PO q12h | IV/PO | Once then q12h | — | 🌎 NA |
| Status epilepticus | 2-5 mg/kg bolus (repeat at 20 min intervals up to 2x), or add to diazepam infusion at 2-10 mg/hour | IV | PRN | — | 🌎 NA |
| Emergency seizure control | 3 mg/kg (repeat q20m up to 24 mg/kg/24h) OR 10 mg/kg bolus | IV | PRN | — | 🌎 NA |
| Sedation (situational distress/travel) | 2-3 mg/kg | PO | PRN | — | 🌎 NA |
- Idiopathic epilepsy (initial dose): Optimum therapeutic levels 23-30 mcg/mL.
- Idiopathic epilepsy (maintenance): Adjust based on serum levels.
- Status epilepticus: If seizures persist after diazepam therapy.
- Emergency seizure control: Given along with IV diazepam.
- Sedation (situational distress/travel): For controlling excessive vocalization.
雪貂
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Seizures | 1-2 mg/kg | PO | q8-12h (2-3 times daily) | — | 🌎 NA |
| Seizures (rapid loading) | Loading dose of 16-20 mg/kg once IV; maintenance dose of 1-2 mg/kg PO q8-12h | IV/PO | q8-12h | — | 🌎 NA |
馬
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Seizures (Adults) | Loading dose of 12 mg/kg IV over 20 minutes, then 6.65 mg/kg IV over 20 minutes q12h | IV | q12h | — | 🌎 NA |
| Seizures (Adults) | Loading dose of 16-20 mg/kg once IV; maintenance dose of 1-5 mg/kg PO twice daily | IV/PO | q12h | — | 🌎 NA |
| Seizures (Foals) | Loading dose of 16-20 mg/kg once IV; maintenance dose of 100-500 mg (total dose) PO twice daily | IV/PO | q12h | — | 🌎 NA |
| Seizures (Foals) | 20 mg/kg diluted and infused over 25-30 minutes IV, then 9 mg/kg infused as above q8h | IV | q8h | — | 🌎 NA |
牛
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Enzyme induction in organochlorine toxicity | 5 grams | PO | Daily | 3-4 weeks on, 3-4 weeks off, repeat | 🌎 NA |
劑量為合格獸醫專業人員的臨床參考。請務必對照最新仿單及個別病患確認。
概覽
苯巴比妥 (Phenobarbital) 是一種長效巴比妥類藥物，在獸醫學中是控制癲癇發作的基石。
- 主要用途：被廣泛認為是治療貓原發性癲癇的首選藥物，同時也是狗和馬最常見且有效的第一線或輔助抗癲癇藥物之一。
- 臨床優勢：具有良好的藥代動力學特性、相對安全性高、療效確切且成本低廉。它能在亞催眠劑量下有效控制癲癇。
- 肝臟自我誘導：苯巴比妥的一個獨特藥理特徵是它能誘導肝臟細胞色素 P450 酵素。隨著時間推移，病患肝臟代謝該藥物的效率會提高，這通常需要增加劑量以維持治療血清濃度。
- 其他用途：除了控制癲癇外，偶爾也用作口服鎮靜劑（例如用於貓咪旅行焦慮或過度鳴叫），並可用於在使用苯二氮平類藥物初步控制後的癲癇重積狀態管理。
作用機轉
Phenobarbital exerts its antiseizure and sedative effects through multiple mechanisms within the central nervous system:
- GABA-A Receptor Modulation: Phenobarbital binds to the allosteric barbiturate site on the GABA-A receptor. Unlike benzodiazepines (which increase the frequency of chloride channel opening), phenobarbital increases the duration of chloride channel opening → enhanced influx of chloride ions → hyperpolarization of the postsynaptic neuronal membrane → increased seizure threshold and decreased spread of seizure activity.
- Glutamate Inhibition: It inhibits the release of excitatory neurotransmitters, specifically glutamate, thereby dampening CNS excitability.
- Calcium Channel Blockade: At high (anesthetic) doses, it inhibits the uptake of calcium at nerve endings, further reducing neurotransmitter release.
- Other Neurotransmitters: It has also been shown to inhibit the release of acetylcholine and norepinephrine.
安全性與警告
禁忌症
- Known hypersensitivity to barbiturates
- Severe liver disease
- Nephritis (large doses)
- Severe respiratory depression
- Hepatic dysfunction
- Severe renal impairment
不良反應
- Dogs: Transient anxiety, agitation, or lethargy upon initiation
- Dogs: Polydipsia (PD), polyuria (PU), and polyphagia (PP)
- Dogs: Sedation and ataxia (especially at higher serum levels)
- Dogs: Elevated liver enzymes (ALT, ALP) - common and not always indicative of failure
- Dogs: Hepatotoxicity (uncommon, usually at levels >30-40 mcg/mL)
- Dogs: Rare blood dyscrasias (anemia, thrombocytopenia, neutropenia)
- Dogs: Rare superficial necrolytic dermatitis (SND)
- Cats: Ataxia, persistent sedation, lethargy
- Cats: Polyphagia, weight gain, PU/PD
- Cats: Rare immune-mediated reactions and bone marrow hypoplasia
- Cats: Coagulopathies (at very high doses)
- Blood dyscrasias (rare)
注意事項
Intravenous Administration: Must be given SLOWLY (not more than 60 mg/minute). Too rapid IV administration may cause profound respiratory depression.
Tissue Irritation: Do NOT administer subcutaneously (SC) or perivascularly. The injectable solution is highly alkaline and very irritating, potentially causing significant tissue necrosis.
- Patient Conditions: Use with extreme caution in patients that are hypovolemic, anemic, have borderline hypoadrenal function, or have pre-existing cardiac or respiratory disease.
- Feline Sensitivity: Cats are particularly sensitive to the respiratory depressant effects of barbiturates.
- Hepatic Function: Chronic administration induces hepatic microsomal enzymes. Monitor liver function closely, especially in dogs, as hepatotoxicity can occur at high serum concentrations.
- Endocrine Testing: Can alter thyroid testing (decreased T4, normal T3, normal/increased TSH) and may cause a false positive low-dose dexamethasone suppression test.
藥物交互作用
Increased risk for hepatotoxicity, particularly with large or chronic doses of barbiturates.
Increased risk for hepatotoxicity secondary to carprofen metabolites.
May prolong phenobarbital effects.
Barbiturates may affect phenytoin metabolism, and phenytoin may alter barbiturate levels.
May induce enzymes that increase the metabolism of barbiturates.
Phenobarbital reduces levetiracetam elimination half-life by about 50% in dogs.
Phenobarbital may decrease anticoagulant effects by lowering serum concentrations.
Phenobarbital increases the metabolism and clearance of corticosteroids, potentially reducing their efficacy.
Phenobarbital decreases doxycycline serum concentrations; effect may persist for weeks after discontinuation.
Phenobarbital increases theophylline metabolism, lowering its serum concentrations.
May increase the effects of phenobarbital while phenobarbital may decrease chloramphenicol levels.
Increased hepatic metabolism and clearance of T4
Inhibits phenobarbital metabolism
監測
- Anticonvulsant efficacy (seizure frequency and severity)
- Adverse effects (CNS depression, ataxia, PU/PD, weight gain)
- Serum phenobarbital levels (Dogs: 20-35 mcg/mL; Cats: 23-30 mcg/mL). Wait 5-6 half-lives (12-14 days in dogs, 9-10 days in cats) before measuring steady-state levels.
- Routine CBC, liver enzymes (especially ALT and AST), and bilirubin at least every 6 months during chronic therapy.
- Serum phenobarbital concentrations (trough levels)
- Liver enzymes (ALT, ALP, GGT)
- Serum bile acids
- Complete Blood Count (CBC)
- Renal function
藥物動力學
半衰期
吸收
Slowly absorbed from the GI tract. Bioavailability is approximately 90% in dogs and practically complete in adult horses. Peak levels occur 4-8 hours after oral dosing in dogs.
分佈
Widely distributed throughout the body. Due to lower lipid solubility compared to other barbiturates, it does not distribute as rapidly into the CNS. Protein binding is 40-60%. Volume of distribution: Dogs ~0.75 L/kg, Horses ~0.8 L/kg.
代謝
Metabolized in the liver primarily by hydroxylated oxidation to p-hydroxyphenobarbital; sulfate and glucuronide conjugates are also formed. Induces hepatic microsomal enzymes, leading to auto-induction and increased clearance over time.
排除
Approximately 25% is excreted unchanged by the kidneys. Alkalinizing the urine or increasing urine flow increases excretion rates.
過量
Clinical Signs of Toxicity:
- Dogs: Ataxia, lethargy, sedation, recumbency, depression, hypothermia, and coma.
- Cats: Ataxia, sedation, and recumbency.
Treatment:
- Decontamination: Removal of ingested product from the gut if recent. Activated charcoal is highly effective and acts as a 'sink' to draw the drug from the vasculature back into the gut, enhancing clearance even if the drug was given parenterally.
- Supportive Care: Provide intensive respiratory and cardiovascular support.
- Enhanced Elimination: Forced alkaline diuresis can substantially augment elimination in patients with normal renal function. Peritoneal dialysis or hemodialysis may be helpful in severe intoxications or anuric patients.
可用產品
劑型
- Tablets
- Capsules
- Oral elixir/suspension
- 12.5 mg oral tablet
- 15 mg oral tablet
- 25 mg oral tablet
- 30 mg oral tablet
- 50 mg oral tablet
- 60 mg oral tablet
- 100 mg oral tablet
- 4% (40 mg/ml) oral solution
- 15 mg/5 ml oral solution
- 15 mg/ml injectable solution
- 30 mg/ml injectable solution
- 60 mg/ml injectable solution
- 200 mg/ml injectable solution
獸醫用
- None currently labeled for veterinary use.
- Epiphen
- Epityl
- Phenoleptil
人用標示
- Phenobarbital Tablets: 15 mg, 16 mg, 30 mg, 60 mg, 90 mg, & 100 mg (Solfoton, generic)
- Phenobarbital Elixir: 15 mg/5mL, 20 mg/5mL (generic)
- Phenobarbital Sodium Injection: 30 mg/mL, 60 mg/mL, 65 mg/mL, & 130 mg/mL (Luminal Sodium, generic)
- Phenobarbital oral solution
各地核准狀態
POM-V, POM CD SCHEDULE 3
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Tablets: Store in tight, light-resistant containers at room temperature (15-30°C); protect from moisture. Elixir: Store in tight containers at 20-25°C. Injection: Store at room temperature (15-30°C). Do not add to acidic solutions or use if precipitate forms.
飼主須知
寵物主人重要指引：
- 一致性是關鍵：為了成功治療癲癇，您必須每天在同一時間給藥。即使只漏掉一劑，也可能引發癲癇發作。
- 初期副作用：剛開始服藥時，您的寵物可能會表現得像「喝醉的水手」（走路搖晃、嗜睡，或異常飢餓/口渴）。這是正常現象，通常在身體適應後的 1 到 2 週內會顯著改善。
- 切勿突然停藥：未經獸醫師同意，絕對不要突然停止給藥，因為這可能導致嚴重且危及生命的癲癇發作。
- 監測：您的獸醫師需要定期抽血以檢查血液中的藥物濃度並監測肝功能。這對您寵物的安全及確保劑量正確至關重要。
- 安全存放：請將此藥物嚴格放置在兒童和其他寵物接觸不到的地方。存放在防兒童開啟的包裝中。
- 何時聯繫獸醫：如果寵物的癲癇發作未能控制、變得極度嗜睡，或者您注意到眼睛/牙齦發黃（黃疸）或嚴重虛弱等跡象，請立即聯繫您的獸醫師。
VetSheet 藥物參考供合格獸醫專業人員作臨床決策輔助之用，不能取代專業判斷或廠商最新仿單。