撲米酮
Primidone
5-ethyldihydro-5-phenyl-4,6(1H,5H)-pyrimidinedione
別名: Mysoline · Neurosyn · hexamidinum · primaclone · primidonum · Cyral · Epidona · Liskantin · Mylepsinum · Prysoline · Resimatil · Sertan
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 |
|---|---|---|---|---|---|
| Seizure control | 10-30 mg/kg per day divided into 2-3 doses | PO | divided into 2-3 doses | — | 🌎 NA |
| Seizure control | 10 mg/kg | PO | q8h | — | 🌎 NA |
- Seizure control: Initially
- Seizure control: Not recommended as first choice
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Seizure control | 20 mg/kg | PO | q12h | — | 🌎 NA |
- Seizure control: Extreme caution advised; many consider contraindicated in cats.
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
撲米酮是一種巴比妥類抗癲癇前驅藥物，在犬隻體內會迅速轉化為苯巴比妥 (Phenobarbital) 和 苯乙基丙二醯胺 (PEMA)。
雖然過去常用於控制犬隻的癲癇發作，但目前多數獸醫神經學專家已不建議將其作為首選藥物。
臨床提示： 與苯巴比妥相比，撲米酮引發嚴重肝毒性的機率較高，這是限制其長期使用的主要原因。
在犬隻中，撲米酮轉化為苯巴比妥的比例約為 4:1（250 毫克的撲米酮約等同於 60 毫克的苯巴比妥）。部分臨床獸醫師會將其保留用於對單獨使用苯巴比妥反應不佳的頑固性病例，理論上 PEMA 代謝物可能增強苯巴比妥的抗癲癇活性。該藥物對貓和兔子具有高度毒性。
作用機轉
Primidone and its active metabolites, phenylethylmalonamide (PEMA) and phenobarbital, exert anticonvulsant effects by raising seizure thresholds and altering seizure patterns.
Mechanistic Pathway:
- Phenobarbital (Primary active metabolite): Binds to the allosteric barbiturate site on GABA_A receptors in the CNS → prolongs the duration of chloride channel opening → increases intracellular chloride influx → hyperpolarizes the postsynaptic neuron → globally depresses CNS excitability and raises the seizure threshold.
- PEMA: Has weak intrinsic anticonvulsant activity but is believed to synergistically potentiate the effects of phenobarbital.
- Primidone (Parent drug): May have some independent action on voltage-gated sodium channels, though its primary efficacy in veterinary species is attributed to its phenobarbital metabolite.
安全性與警告
禁忌症
- Severe liver disease
- Demonstrated previous hypersensitivity to primidone or barbiturates
- Nephritis (large doses contraindicated)
- Severe respiratory dysfunction (large doses contraindicated)
- Cats (considered contraindicated by many clinicians due to high toxicity risk)
不良反應
- Anxiety and agitation (especially during initiation)
- Elevated liver enzymes (ALT, ALP, GLDH)
- Decreased serum albumin
- Hepatic lipidosis
- Hepatocellular hypertrophy and necrosis
- Extramedullary hematopoiesis
- Depression and sedation
- Ataxia
- Polydipsia (PD)
- Polyuria (PU)
- Polyphagia
- Anorexia
- Tachycardia
- Dermatitis
- Episodic hyperventilation
- Urolith formation (primidone uroliths reported)
- Megaloblastic anemia (rare)
注意事項
Species Warnings: Use with extreme caution, if at all, in cats. Primidone is considered highly toxic to felines.
Patient Conditions: Use cautiously in patients who are hypovolemic, anemic, have borderline hypoadrenal function, or have cardiac or respiratory disease.
Drug Transition: When converting dogs from primidone to phenobarbital, it is suggested to do this slowly (tapering 1/4 of the dose each month) to prevent withdrawal seizures.
Laboratory Interference: Barbiturates may cause falsely elevated bromosulfophthalein (BSP) retention. Primidone/phenobarbital can alter thyroid testing (decreased total and free T4, normal T3, normal/increased TSH); wait at least 4 weeks after discontinuation to perform thyroid testing. 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.
Oral administration may decrease the GI absorption of primidone.
May prolong phenobarbital effects.
Barbiturates may affect phenytoin metabolism, and phenytoin may alter barbiturate levels; therapeutic monitoring indicated.
May induce enzymes that increase the metabolism of barbiturates.
May increase the CNS depressant effects of phenobarbital.
May increase the effects of phenobarbital; phenobarbital may also decrease chloramphenicol levels.
May increase the CNS depressant effects of phenobarbital.
May increase the effects of phenobarbital; phenobarbital may decrease phenothiazine serum concentrations.
May increase the effects of phenobarbital.
Phenobarbital may decrease anticoagulant effects by lowering serum concentrations.
Phenobarbital may decrease effects by lowering serum concentrations.
Phenobarbital may decrease effects by lowering serum concentrations.
Phenobarbital may decrease effects by lowering serum concentrations.
Phenobarbital may decrease effects by lowering serum concentrations (effect may persist for weeks after barbiturate is discontinued).
Phenobarbital may decrease effects by lowering serum concentrations.
監測
- Anticonvulsant efficacy (seizure frequency and severity)
- Adverse effects (CNS depression, PU/PD, weight gain, signs of liver disease)
- Serum phenobarbital levels (therapeutic range in dogs thought to be 15-40 mcg/mL) if lack of efficacy or adverse reactions are noted
- Routine CBCs and liver enzyme panels at least every 6 months during chronic therapy
藥物動力學
半衰期
吸收
Slowly absorbed after oral administration in the dog, with peak levels occurring 2-4 hours after dosing. Bioavailability in humans is reported as 60-80%.
分佈
Appears in maternal milk in substantial quantities.
代謝
Rapidly converted to phenylethylmalonamide (PEMA) and phenobarbital in the dog. Induces hepatic microsomal enzymes, increasing the rate of metabolism of itself and other drugs.
排除
Eliminated primarily via hepatic metabolism to active metabolites, which are subsequently cleared.
過量
Clinical Signs: Because primidone is rapidly metabolized to phenobarbital in dogs, signs of acute toxicity mirror barbiturate overdose: sedation progressing to coma, anorexia, vomiting, ataxia, and nystagmus.
Treatment:
- Decontamination: Removal of ingested product from the gut if appropriate (emesis or gastric lavage).
- Adsorbents: Activated charcoal is of considerable benefit in enhancing the clearance of phenobarbital (acts as a 'sink' for the drug to diffuse from the vasculature back into the gut), even if the drug was administered parenterally.
- Supportive Care: Provide respiratory and cardiovascular support.
- Enhanced Elimination: Forced alkaline diuresis can 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
- Oral suspension
獸醫用
- Primidone Tablets: 50 mg and 250 mg (Neurosyn®)
人用標示
- Primidone Tablets: 50 mg and 250 mg (Mysoline®, generic)
各地核准狀態
暫無法規資料: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Tablets should be stored in well-closed containers, preferably at room temperature. Oral suspension should be stored in tight, light-resistant containers at room temperature; avoid freezing. Commercially available products generally have a 5-year expiration date.
飼主須知
成功的關鍵： 嚴格遵守用藥指示是成功治療癲癇的關鍵。請務必每天在完全相同的時間給藥。
- 行為改變： 在剛開始服藥時，您的寵物可能會顯得焦慮、躁動或異常嗜睡。這些反應通常是暫時的，會隨著身體適應而改善。
- 食慾與飲水量增加： 您可能會發現寵物喝水、排尿和進食的量比平常多。請監測牠們的體重，並與獸醫師討論飲食管理。
- 何時應聯繫獸醫師： 如果您的寵物出現嚴重嗜睡、食慾不振、嘔吐、眼睛或牙齦發黃（黃疸）、牙齦蒼白，或者癲癇發作未能有效控制，請立即聯繫獸醫師。
- 切勿突然停藥： 在未經獸醫師指導的情況下，絕對不可突然停止給藥，否則可能引發嚴重且危及生命的癲癇發作。
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