左乙拉西坦
**左乙拉西坦 (Levetiracetam)** 是一種新型且結構獨特的抗癲癇藥物，在獸醫學中主要作為輔助治療。 * **犬：** 作為難治性癲癇的第三線藥物，或在苯巴比妥/溴化鉀有禁忌或耐受不良時使用。需注意犬隻長期使用可能出現「蜜月期效應」（療效隨時間下降）。 * **貓：** 通常在苯巴比妥療效不足時作為二線附加藥物，或在無法耐受苯巴比妥時作為單一療法。 **臨床要點：** 該藥物極少經肝臟代謝，且不依賴細胞色素 P450 系統，因此非常適合肝功能受損的病患。然而，其半衰期短，需要頻繁給藥（一天三次），對飼主而言可能是一大挑戰。
作用機制: The exact mechanism of levetiracetam's antiseizure activity is not fully elucidated, but it is distinct from traditional anticonvulsants (which typically affect GABA or ion channels). * Binds specifically to **Synaptic Vesicle Protein 2A (SV2A)** in the central nervous system. * Binding to **SV2A** → modulates neurotransmitter release into the synaptic cleft → selectively prevents hypersynchronization of epileptiform burst-firing and propagation of seizure activity. * It does **not** affect normal neuronal excitability.
各物種劑量
- As an add-on to phenobarbital treatment for epilepsy · Initially, 20 mg/kg PO three times daily; slowly increase to effect · PO · TID
- As an adjunct to phenobarbital in suspected idiopathic epilepsy · Initially, 20 mg/kg PO three times daily. Monitor as below. If ineffective, increase dose in 20 mg/kg increments. · PO · TID
- As an add-on treatment for epilepsy in dogs refractory to phenobarbital and bromides · 20 mg/kg PO every 8 hours · PO · q8h
- As an add-on treatment for epilepsy in dogs refractory to phenobarbital and/or bromides · 7.1-23.8 mg/kg PO every 8 hours · PO · q8h
- Seizure management · 10-20 mg/kg PO q8h · PO · q8h
- Seizure management · Initially, 20 mg/kg PO q8h. May increase dose in 20 mg/kg increments until efficacy achieved, side effects become apparent, or the drug becomes cost prohibitive. · PO · q8h
- Seizure management · 20 mg/kg PO q8h; may also be given as an IV bolus (20 mg/kg). · PO/IV · q8h
- Single-dose pharmacokinetic study · 60 mg/kg IV bolus dose · IV · Once · Well tolerated and achieves plasma drug concentrations within or above the therapeutic range reported for humans for at least 8 hours.
- For status epilepticus · Initially, lorazepam at 0.2 mg/kg IV once, followed by a bolus IV loading dose of levetiracetam at 60 mg/kg. · IV · Once
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to levetiracetam or any of its components
- Severe renal disease
不良反應
- Sedation (most common in dogs)
- Lethargy (most common in cats)
- Decreased appetite (most common in cats)
- Behavior changes
- Gastrointestinal effects
- Sedation (dogs)
- Ataxia (dogs)
- Reduced appetite (cats)
- Hypersalivation (cats)
- Lethargy (cats)
藥物相互作用
- NSAIDs (naproxen, ketorolac) · May increase the risk for seizures (reported in humans; veterinary significance unclear).
- Phenobarbital · Significantly increases levetiracetam clearance and reduces its half-life in dogs (from 3.43 hrs to 1.73 hrs); dosage adjustments may be required. · moderate
監測
- Therapeutic drug monitoring (target range 5-45 mcg/mL) approximately one week after starting, then every 6-12 months (primarily to adjust dosage)
- Seizure activity log (frequency, duration, severity)
- Routine CBC and basic metabolic panel every 6 months
- Adverse effects (sedation, lethargy, appetite changes)
- Seizure frequency and severity
- Renal function (BUN, Creatinine, SDMA) especially in older patients
- Therapeutic drug monitoring is rarely required but can be performed
過量
Levetiracetam is a relatively safe agent. * **Dogs:** Doses of 1200 mg/kg/day (~20x therapeutic dose) caused only salivation and vomiting. * **Humans:** Doses of 6000 mg/kg caused drowsiness. Other reported effects include depressed consciousness, agitation, aggression, and respiratory depression. * **Treatment:** Basically supportive. The drug can be removed with hemodialysis. Contact an animal poison control center for significant overdoses.
VetSheet 藥物參考供持牌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方最新藥品說明書。