レベチラセタム
**レベチラセタム**は、主に獣医療において補助療法として使用される、構造的にユニークな新規の抗てんかん薬です。 * **犬：** フェノバルビタールや臭化カリウムが禁忌または忍容性が低い場合、あるいは難治性てんかんの三次選択薬として使用されます。犬では長期投与により効果が減弱する「ハネムーン効果」が見られることがある点に注意が必要です。 * **猫：** 通常、フェノバルビタールで十分な効果が得られない場合の二次追加薬として、またはフェノバルビタールに忍容性がない場合の単剤療法として使用されます。 **臨床のポイント：** 肝臓での代謝がごくわずかであり、シトクロムP450酵素系に依存しないため、肝機能障害のある患者に非常に適しています。ただし、半減期が短いため頻回（1日3回）の投薬が必要であり、飼い主にとって負担になることがあります。
作用機序: 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.
動物種別の用量
- 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
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Hypersensitivity to levetiracetam or any of its components
- Severe renal disease
有害事象
- 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)
薬物相互作用
- 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
モニタリング
- 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
過量投与
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 の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。