カルバマゼピン
カルバマゼピンは、三環系抗うつ薬イミプラミンと化学的に関連するジベンゾアゼピンイミノスチルベン誘導体です。 > **臨床上のポイント：** ヒト医療では主要な抗てんかん薬および気分安定薬として広く使用されていますが、獣医療（特に犬）での有用性は、急速な肝臓の自己誘導（オートインダクション）によって厳しく制限されます。犬は治療開始後数日でこの薬物を非常に速く代謝するため、治療的な血清濃度を維持することが極めて困難になります。 この薬物動態学的な制限のため、動物のてんかん発作のコントロールに使用されることは稀です。その代わり、獣医療では主に以下の目的で使用されます： * 犬の**行動治療**（例：扁桃体の過活動や爆発的な攻撃性の管理。しばしばSSRIと併用される）。 * 馬の**神経障害性疼痛**や、シプロヘプタジンなどの他の治療に反応しない**光過敏性ヘッドシェイキング**などの特定の神経疾患。
作用機序: Carbamazepine primarily acts by **blocking voltage-gated sodium channels** in neuronal membranes. * **Mechanism:** Binds preferentially to the inactive state of sodium channels → delays their recovery → **inhibits repetitive neuronal firing** and stabilizes hyperexcited neural membranes. * It also decreases the synaptic transmission of excitatory impulses and may reduce the release of the excitatory neurotransmitter glutamate. * Structurally related to tricyclic antidepressants, it also possesses mild anticholinergic, antidiuretic, and muscle relaxant properties.
動物種別の用量
- For photic head shaking · 10 mg/kg PO q6h or 29 mg/kg PO q12h · PO · q6h or q12h · May be helpful in some horses that do not respond to cyproheptadine.
- As a psychotherapeutic agent · 4-8 mg/kg PO q12h · PO · q12h · Not commonly used, but may have some utility in dogs that seem to have amygdalar hyperactivity; sometimes used in conjunction with SSRIs to control explosive aggression.
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
- Patients receiving MAO Inhibitors (e.g., selegiline) within the past 14 days
- Patients with a history of bone marrow depression
- Known hypersensitivity to carbamazepine or tricyclic antidepressants
有害事象
- Sedation and lethargy
- Ataxia (unsteadiness)
- Gastrointestinal upset (vomiting, anorexia)
- Hepatotoxicity (elevated liver enzymes)
- Blood dyscrasias (rare but possible bone marrow suppression)
薬物相互作用
- Azole Antifungals (e.g., Ketoconazole, Itraconazole) · May increase plasma levels or effects of carbamazepine
- Calcium Channel Blockers (e.g., Diltiazem, Verapamil) · May increase plasma levels or effects of carbamazepine; Carbamazepine may also decrease their effects
- Cimetidine · May increase plasma levels or effects of carbamazepine
- Danazol · May increase plasma levels or effects of carbamazepine
- Grapefruit Juice · May increase plasma levels or effects of carbamazepine
- Isoniazid · May increase plasma levels or effects of carbamazepine; Carbamazepine may also increase effects of Isoniazid
- Macrolides (e.g., Erythromycin, Clarithromycin) · May increase plasma levels or effects of carbamazepine
- MAO Inhibitors (e.g., Selegiline) · Contraindicated; discontinue MAOI at least 14 days prior to carbamazepine
- Niacin · May increase plasma levels or effects of carbamazepine
- SSRI Antidepressants (e.g., Fluoxetine) · May increase plasma levels or effects of carbamazepine
- Tricyclic Antidepressants (e.g., Clomipramine, Amitriptyline) · May increase plasma levels or effects of carbamazepine; Carbamazepine may also decrease their effects, though it can increase Clomipramine levels
モニタリング
- Complete Blood Count (CBC)
- Liver function tests
- Clinical efficacy and behavioral changes
過量投与
Overdose can lead to significant CNS depression, severe ataxia, tremors, seizures, respiratory depression, and cardiovascular abnormalities (tachycardia, hypotension). Treatment is primarily supportive and symptomatic, including gastric decontamination if caught early, IV fluids, and respiratory support. Seizures should be treated with standard anticonvulsants (e.g., diazepam, phenobarbital).
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。