唑尼沙胺
Zonisamide
1,2-benzisoxazole-3-methanesulfonamide
別名: Zonegran · Excegran · AD-810 · CI-912 · PD-110843 · Zonisamidum
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 |
|---|---|---|---|---|---|
| Refractory epilepsy (with phenobarbital) | 5-10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Monotherapy | Initially at 5 mg/kg PO twice daily (q12h) | PO | q12h | — | 🌎 NA |
| Add-on with phenobarbital | 10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Initial monotherapy | 3-5 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Add-on agent | 10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Epilepsy | 5-10 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Epilepsy (monotherapy or adjunctive) | 5-10 mg/kg | PO | q12h | Long-term | 🌍 EU |
- Refractory epilepsy (with phenobarbital): The high end of the dose range is needed when used in combination with phenobarbital due to microsomal enzyme induction.
- Epilepsy: Gradual adaptation in dosing is recommended. Reduce phenobarbital doses by 25% at the time of starting zonisamide.
- Epilepsy (monotherapy or adjunctive): Start at 5 mg/kg q12h. If the dog is concurrently receiving phenobarbital, start at 10 mg/kg q12h due to induced metabolism.
貓
| 適應症 | 劑量 | 途徑 | 頻次 | 療程 | 地區 |
|---|---|---|---|---|---|
| Epilepsy (anecdotal) | 5 mg/kg PO every 12-24 hours | PO | q12-24h | — | 🌎 NA |
| Refractory to phenobarbital | 5-10 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Epilepsy | 10-20 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Epilepsy | 5-10 mg/kg | PO | q24h | Long-term | 🌍 EU |
- Epilepsy (anecdotal): Most commonly utilized anecdotal dose.
- Refractory to phenobarbital: Long half-life makes once daily dosing likely appropriate.
- Epilepsy: Longer half-life in cats allows for once-daily dosing.
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
唑尼沙胺是一種苯并異噁唑衍生物，屬於磺胺類抗癲癇藥物。在獸醫學中，主要用於犬貓難治性特發性癲癇的輔助治療或單一療法。
- 臨床重點：由於其肝臟代謝負擔低於苯巴比妥，常被優先用於需要避免肝臟毒性的病患。
- 其在小動物體內具有良好的藥代動力學特性，犬的半衰期約為15小時（可每日給藥兩次），貓約為33小時（可每日給藥一次）。
- 與人類不同，唑尼沙胺在犬隻標準劑量下呈現線性藥代動力學。
作用機轉
The exact mechanism of action is multifactorial and not completely elucidated:
- Blocks voltage-gated sodium channels and reduces transient inward currents → stabilizes neuronal membranes and suppresses neuronal hypersynchronization.
- Inhibits T-type voltage-gated calcium channels.
- Acts as a weak carbonic anhydrase inhibitor.
- Note: Unlike diazepam or phenobarbital, it does not appear to potentiate GABAergic activity.
安全性與警告
禁忌症
- Hypersensitivity to zonisamide
- Hypersensitivity to sulfonamide drugs
- Pregnancy (known teratogen in dogs)
- Hypersensitivity to sulfonamides
- Severe hepatic impairment
不良反應
- Sedation (usually transient)
- Ataxia
- Inappetence / Anorexia
- Vomiting
- Diarrhea
- Somnolence
- Keratoconjunctivitis sicca (KCS) - theoretical risk due to sulfonamide structure
- Polyarthropathy or blood dyscrasias - theoretical risk due to sulfonamide structure
- Hepatotoxicity (rare)
- Metabolic acidosis
注意事項
Teratogenic Risk: Zonisamide is a known teratogen in dogs. Doses of 10-30 mg/kg/day have caused ventricular septal defects, cardiomegaly, and valvular/arterial anomalies (threshold plasma level for malformation is 25 mcg/mL). Use in pregnant dogs carries significant risks.
- Sulfonamide Sensitivity: Because it is a sulfonamide, monitor for idiosyncratic sulfonamide reactions (e.g., KCS, blood dyscrasias), though clinical reports in veterinary patients are currently rare.
- Use with caution in nursing animals as it is unknown if it enters maternal milk.
藥物交互作用
Increases the clearance of zonisamide. Repeated phenobarbital dosing decreases the bioavailability, peak concentrations, half-life, and AUC of zonisamide. This effect can persist up to 10 weeks after phenobarbital discontinuation. Higher zonisamide doses are typically required.
May inhibit the hepatic metabolism of zonisamide, potentially increasing serum concentrations.
監測
- Clinical efficacy (seizure frequency and severity)
- Serum zonisamide concentrations (suggested therapeutic range in dogs: 10-40 mcg/mL)
- Adverse effects (sedation, ataxia, GI upset)
- Schirmer tear test (monitor for KCS due to sulfonamide structure)
- Serum zonisamide concentrations (therapeutic target typically 10-40 µg/mL)
- Schirmer Tear Test (STT) periodically
- Liver enzymes and bilirubin
- Complete Blood Count (CBC)
藥物動力學
半衰期
吸收
Well absorbed after oral administration in dogs with a bioavailability of about 70%. Can also be absorbed rectally.
分佈
Low protein binding.
代謝
About 20% is metabolized, primarily in the liver.
排除
Most of the drug is excreted via the kidneys into the urine.
過量
The LD50 of zonisamide in dogs is reportedly 1 gram/kg.
In human overdoses, reported effects include coma, bradycardia, hypotension, and respiratory depression.
Treatment:
- GI evacuation if ingestion was recent.
- Supportive and symptomatic therapy.
- Because of the drug's long half-life, supportive care may be required for several days.
可用產品
劑型
- Capsules: 25 mg, 50 mg, 100 mg
- 25 mg capsule
- 50 mg capsule
- 100 mg capsule
人用標示
- Zonisamide Capsules: 25 mg, 50 mg & 100 mg (Zonegran®, generic)
- Zonegran 25 mg capsules
- Zonegran 50 mg capsules
- Zonegran 100 mg capsules
各地核准狀態
Human authorized product (Zonegran) used off-label under the cascade.
Human authorized product (Zonegran) used off-label under the cascade.
暫無法規資料: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
儲存與穩定性
Store capsules at 25°C (76°F); excursions permitted to 15-30°C (59-86°F). Store in a dry place and protect from light.
飼主須知
- 嚴格遵守給藥時間：請務必按照處方準時給藥，漏服可能導致癲癇發作。
- 切勿自行停藥：突然停藥可能引發嚴重的「反彈性」癲癇。在調整劑量前請務必諮詢獸醫師。
- 癲癇日記：請詳細記錄寵物癲癇發作的日期、時間、持續時間及嚴重程度，以協助獸醫師準確調整劑量。
- 副作用：初期可能會出現輕微的嗜睡或步伐不穩，但通常會隨著寵物適應藥物而改善。如果寵物出現食慾不振、嘔吐或眼睛乾澀發紅，請立即聯繫獸醫師。
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