ブスピロン
ブスピロン（Buspirone）は、アザピロン系の非ベンゾジアゼピン系抗不安薬です。主に獣医学において、犬や猫の全般性不安、軽度の恐怖症、および猫の尿スプレー行動の管理に使用されます。 ベンゾジアゼピン系とは異なり、鎮静、筋弛緩、抗痙攣作用を持たないため、顕著な認知機能や精神運動機能の障害を引き起こすことなく、長期的な行動管理に最適です。 **臨床上のポイント:** * **遅延性の効果発現:** 受容体密度を変化させ、完全な臨床効果を得るには、慢性的な投与（通常1〜4週間）が必要です。 * **急性のパニックには不適:** 効果発現が遅いため、急性の状況的パニック（例：雷雨への即時反応や急性の分離不安の発作）に対する単独療法としては不適切であり、効果がありません。 * **社会的ダイナミクス:** 社会的相互作用に関連する不安に特に有用であり、単頭飼いよりも多頭飼いの環境でより効果的である可能性があります。
作用機序: Buspirone is an anxioselective agent that acts primarily as a partial agonist at **serotonin (5-HT1A) receptors** and as an agonist/antagonist at presynaptic **dopamine (D2) receptors** in the CNS. * **Serotonin Pathway:** By binding to 5-HT1A autoreceptors → it slows the neuronal firing rate → decreasing the depletion of serotonin stores and modulating serotonergic tone over time. * **Receptor Specificity:** It does **not** share mechanisms with benzodiazepines; it has no significant affinity for benzodiazepine receptors and does not affect GABA binding.
動物種別の用量
- Adjunctive treatment of low-grade anxieties/fears, spraying, overgrooming · 0.5-1 mg/kg PO q8-12h; 2.5-5 mg (total dose) per cat PO q8-12h · PO · q8-12h · 6-8 weeks · some cats do well on once daily dosing
- Adjunctive treatment of low-grade anxieties/fears, spraying, overgrooming · 2.5-5 mg (total dose) PO once a day to 3 times a day · PO · q8-24h
- Urine marking · 2.5-7.5 mg (total dose) per cat PO q12h · PO · q12h
- Adjunctive treatment of low-grade anxieties/fears, spraying, overgrooming · 0.5-1 mg/kg PO q12h; 2.5-7.5 mg (total dose) per cat PO q12h · PO · q12h
- Social phobias, panic disorders · 0.5-1 mg/kg PO q8-12h · PO · q8-12h · most useful in social phobias; may also be useful for panic disorders
- Low-grade anxieties and fears · 1 mg/kg PO q8-24h (mild anxiety); 2.5-10 mg (total dose) per dog PO q8-24h (mild anxiety); 10-15 mg per dog PO q8-12h (more severe anxiety, thunderstorm phobia) · PO · q8-24h or q8-12h
- Low-grade anxieties and fears · 1-2 mg/kg PO q12h; 5-15 mg (total dose) per dog PO q8-12h · PO · q8-12h or q12h
- Low-grade anxieties and fears · 5-10 mg (total dose) PO q8-12h · PO · q8-12h
- Global anxiety · 0.5-2 mg/kg PO q8-12h · PO · q8-12h · may take 2-4 weeks until effect
投与経路
禁忌
- Severe hepatic disease (use with caution)
- Severe renal disease (use with caution)
- Aggressive animals (may reduce disinhibition)
- Working dogs (use with caution despite low sedation)
- Acute situational anxieties (as sole therapy)
有害事象
- Bradycardia
- Gastrointestinal disturbances
- Stereotypic behaviors
- Increased affection (cats)
- Paradoxical aggression/turning on attackers (previously timid cats)
- Dizziness (humans)
- Headache (humans)
- Nausea/anorexia (humans)
- Restlessness (humans)
- Tachycardia (rare)
薬物相互作用
- Tricyclic or SSRI agents · May be used in combination, but dosage reductions may be necessary to minimize adverse effects
- CNS Depressants · Potentially could cause increased CNS depression
- Diltiazem · May cause increased buspirone plasma levels and adverse effects
- Erythromycin · May cause increased buspirone plasma levels and adverse effects
- Grapefruit juice (powder) · May cause increased buspirone plasma levels and adverse effects
- Ketoconazole, Itraconazole · May cause increased buspirone plasma levels and adverse effects
- Monoamine Oxidase Inhibitors (e.g., selegiline, amitraz) · Use with buspirone is not recommended because dangerous hypertension may occur
- Rifampin · May cause decreased buspirone plasma levels
- Trazodone · Use with buspirone may cause increased ALT
- Verapamil · May cause increased buspirone plasma levels
モニタリング
- Efficacy (reduction in anxiety, spraying, or fear behaviors)
- Adverse effect profiles (GI upset, behavioral changes)
過量投与
Limited information is available in veterinary species. The oral LD50 in dogs is 586 mg/kg. **Clinical Signs of Overdose:** * Vomiting * Dizziness * Drowsiness * Miosis (constricted pupils) * Gastric distention **Treatment:** Standard overdose protocols (e.g., decontamination, supportive care) should be followed after ingestion has been determined.
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。