フルボキサミン
**フルボキサミン**は選択的セロトニン再取り込み阻害薬（SSRI）であり、犬や猫の攻撃性や常同行動（強迫性障害）などの様々な行動障害の治療に使用されます。 フルオキセチンほど一般的には処方されませんが、行動管理の代替薬として機能します。 **臨床上のポイント**: - 他のSSRIと同様に、神経受容体のダウンレギュレーションに時間がかかるため、完全な臨床効果が現れるまでに長期間（通常**6〜8週間**）の継続投与が必要です。 - 急に投与を中止すべきではありません。離脱症状を避けるため、3〜5週間かけて徐々に減量することが推奨されます。 - 食欲不振は犬でよく見られる副作用ですが（通常は一過性）、手から直接食べさせたり、食事の嗜好性を高めることで管理できる場合があります。
作用機序: Fluvoxamine acts by highly selective inhibition of the **serotonin transporter (SERT)** in the central nervous system. **Mechanism:** Blockade of presynaptic reuptake → increased concentration of **serotonin (5-HT)** in the synaptic cleft → prolonged receptor stimulation. Over time, this chronic elevation leads to the down-regulation and desensitization of post-synaptic 5-HT receptors, which correlates with the delayed onset of clinical behavioral improvement. It has minimal to no effect on dopamine or norepinephrine reuptake.
動物種別の用量
- For treatment of compulsive disorders · 0.25-0.5 mg/kg PO once daily · PO · q24h
- For treatment of behavioral diagnoses · 0.25-0.5 mg/kg PO q24h · PO · q24h · Treat for 3-5 weeks minimum to assess effects; then treat until 'well' (minimum another 1-2 months). Continue for another 1-2 months minimum. · Treatment should last for a minimum 4-6 months once initiating therapy. If weaning off, do so over 3-5 weeks (or longer).
- For spraying · 0.25 mg/kg PO q12h · PO · q12h · Avoid use with benzodiazepines
- For treatment of behavioral diagnoses · 0.5-1 mg/kg PO once daily (q24h) · PO · q24h · allow 8 weeks for initial trial
- For treatment of compulsive disorders · 0.5-2 mg/kg PO twice daily · PO · q12h
- For treatment of behavioral diagnoses · 1-3 mg/kg PO once daily (q24h) · PO · q24h · allow 8 weeks for initial trial
- For treatment of behavioral diagnoses · 1 mg/kg PO q12-24h · PO · q12-24h · Treat for 3-5 weeks minimum to assess effects; then treat until 'well' (minimum another 1-2 months). Continue for another 1-2 months minimum. · Treatment should last for a minimum 4-6 months once initiating therapy. If weaning off, do so over 3-5 weeks (or longer).
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 with known hypersensitivity to fluvoxamine or other SSRIs
- Concurrent use of Monoamine Oxidase Inhibitors (MAOIs) such as selegiline or amitraz
- Concurrent use of cisapride
有害事象
- Anorexia/decreased appetite (common)
- Lethargy or sedation
- Gastrointestinal upset (vomiting, diarrhea)
- Anxiety, irritability, or agitation
- Insomnia or hyperactivity
- Panting (dogs)
- Changes in elimination patterns (cats)
- Paradoxical aggressive behavior in previously non-aggressive dogs
薬物相互作用
- Buspirone · Fluvoxamine may paradoxically decrease the clinical efficacy of buspirone.
- Cisapride · Fluvoxamine may increase plasma levels of cisapride, leading to toxicity. Concurrent use is contraindicated.
- Cyproheptadine · May decrease or reverse the effects of SSRIs (useful in treating serotonin syndrome).
- Diazepam, Alprazolam, Midazolam · Fluvoxamine may increase diazepam (and other benzodiazepine) levels.
- Diltiazem · Fluvoxamine may increase the effects of diltiazem; bradycardia has been reported in humans.
- MAO Inhibitors (e.g., amitraz, selegiline) · High risk for serotonin syndrome; contraindicated. A 5-week washout is required after stopping fluvoxamine, and a 2-week washout if stopping the MAOI first.
- Methadone · Fluvoxamine may increase plasma levels of methadone, leading to toxicity.
- Phenytoin · Increased plasma levels of phenytoin possible.
- Propranolol, Metoprolol · Fluvoxamine may increase these beta-blockers' plasma levels; atenolol may be safer.
- Theophylline · Fluvoxamine may increase plasma levels of theophylline.
- Tramadol · SSRIs can inhibit the metabolism of tramadol to active metabolites, decreasing efficacy and increasing toxicity risk (serotonin syndrome, seizures).
モニタリング
- Clinical efficacy (behavioral improvement)
- Adverse effects, particularly appetite and body weight
- Baseline liver function tests (consider re-testing as needed)
- ECG (consider baseline and re-test as needed)
過量投与
Limited data exists for animals. Any dosage over **10 mg/kg** can reportedly cause tremors and lethargy. **Clinical Signs of Overdose:** Vomiting, somnolence/coma, tremors, diarrhea, hypotension, heart rate/rhythm disturbances (bradycardia/tachycardia, ECG changes), and seizures. Fatalities have been reported in human overdoses. **Treatment:** - Standard protocols for GI decontamination (drug adsorption/removal) for potentially dangerous overdoses. - Symptomatic and supportive therapy. - **Serotonin Syndrome Management:** Cyproheptadine (1.1 mg/kg PO or rectally) may be used as an adjunctive treatment to negate serotonin effects. - **Seizure Control:** Diazepam may be used to treat seizures or other severe neurologic signs.
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。