フルオキセチン
Fluoxetine
Fluoxetine hydrochloride
別名: Prozac · Reconcile · Sarafem · fluoxetini hydrochloridum · LY110140 · Fluoxetine hydrochloride
VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス
用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。
動物種別用量
🌎 NA — North America🌍 EU — Europe
犬
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Treatment of canine separation anxiety in conjunction with a behavior modification plan | 1-2 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Separation anxiety and noise aversions | 1-2 mg/kg PO once daily | PO | q24h | Continue until 2 months after satisfactory response, then discontinue gradually | 🌎 NA |
| Adjunctive pharmacological intervention for conflict-related aggression | 1-2 mg/kg PO once a day | PO | q24h | — | 🌎 NA |
| Compulsive disorders | 1-2 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of behavior disorders | 1-1.5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Adjunctive treatment of behavior disorders | 1 mg/kg PO once daily (up to 3 mg/kg PO once daily) | PO | q24h | — | 🌎 NA |
| Separation anxiety, compulsive disorders, and aggression | 1-2 mg/kg | PO | q24h | Long-term as directed | 🌍 EU |
- Separation anxiety and noise aversions: Use with behavioral therapy. May use long-term. Some dogs require life-long treatment. May add a benzodiazepine during seasonal noise fears.
- Adjunctive pharmacological intervention for conflict-related aggression: May take up to 4 weeks for efficacy.
- Separation anxiety, compulsive disorders, and aggression: Use in association with a behaviour modification plan. Caution with aggression.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| Adjunctive treatment of aggression | 0.5-1.5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| To help control urine marking or separation anxiety | 0.5-1 mg/kg (2.55 mg per cat) PO once daily | PO | q24h | — | 🌎 NA |
| To control pruritus when other therapies have failed | 1-5 mg/cat PO once daily | PO | q24h | Assess therapy after 1-4 weeks. Taper off dose over 6-8 weeks. | 🌎 NA |
| Generalized anxiety disorder | 0.5-1.5 mg/kg PO once daily | PO | q24h | — | 🌎 NA |
| Urine spraying, psychogenic alopecia, and aggression | 0.5-1.0 mg/kg | PO | q24h | Long-term as directed | 🌍 EU |
- To control pruritus when other therapies have failed: Advise obtaining baseline lab work.
- Urine spraying, psychogenic alopecia, and aggression: Similar precautions for aggression apply as in dogs.
用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。
概要
フルオキセチン (Fluoxetine) は、獣医療において犬や猫のさまざまな行動障害の管理に広く使用されている選択的セロトニン再取り込み阻害薬 (SSRI) の抗うつ薬です。
犬では、行動修正プランと併用して分離不安を治療する薬としてFDAに承認されています（商品名：Reconcile®）。また、攻撃性、常同行動（強迫性障害）、全般性不安に対しても適応外で使用されます。猫では、不適切な排泄（尿マーキング）、攻撃性、不安、心因性脱毛/そう痒症に対して頻繁に処方されます。
臨床のポイント： フルオキセチンは、完全な臨床効果が現れるまでに通常 4〜8週間 のタイムラグが必要です。これはシナプス後受容体のダウンレギュレーションに時間がかかるためです。飼い主には、この初期段階において忍耐強く投薬を続けるよう指導する必要があります。
作用機序
Fluoxetine acts by selectively binding to and inhibiting the presynaptic serotonin transporter (SERT) in the central nervous system.
- Inhibition of Reuptake: Blockade of SERT prevents the reuptake of serotonin (5-HT) into the presynaptic neuron.
- Increased Synaptic Serotonin: This leads to an accumulation of serotonin in the synaptic cleft → prolonged activation of postsynaptic 5-HT receptors.
- Receptor Downregulation: Chronic elevation of synaptic serotonin eventually leads to the downregulation and desensitization of autoreceptors (e.g., 5-HT1A), which correlates with the onset of anxiolytic, anticompulsive, and anti-aggressive clinical effects.
Fluoxetine has minimal affinity for other neurotransmitter receptors (such as dopamine, norepinephrine, histamine, or acetylcholine), which accounts for its relatively favorable side effect profile compared to tricyclic antidepressants (TCAs).
安全性・警告
禁忌
- Known hypersensitivity to fluoxetine
- Concurrent use of Monoamine Oxidase Inhibitors (MAOIs), including selegiline and amitraz (found in some tick collars)
- Patients with epilepsy or a history of seizures
- Concurrent use with drugs that lower the seizure threshold (e.g., acepromazine, chlorpromazine)
- Known sensitivity to fluoxetine or other SSRIs
- History of seizures or epilepsy
有害事象
- Anorexia or decreased appetite (common, often transient)
- Lethargy or depression
- Gastrointestinal upset (vomiting, diarrhea)
- Anxiety, irritability, or restlessness
- Insomnia or hyperactivity
- Panting (dogs)
- Changes in elimination patterns (cats)
- Paradoxical aggressive behavior (in previously unaggressive animals)
- Seizures (rare but possible)
- Weight loss
- Trembling
- Gastrointestinal disturbances
- Paradoxical increase in anxiety
- Increased aggression
注意事項
- Seizure Disorders: Use is contraindicated in patients with a history of seizures.
- Diabetes Mellitus: Use with caution as fluoxetine may alter blood glucose levels, necessitating insulin adjustments.
- Hepatic Impairment: Dosages may need to be reduced in patients with severe liver disease due to decreased clearance.
- Tapering: Because of the long half-life of the active metabolite (norfluoxetine), tapering off the drug is generally only necessary when a patient has been on the drug long-term (>8 weeks).
- Pregnancy/Nursing: Safety is not fully established (FDA Category C in humans). Excreted in milk at 20-30% of plasma levels; use caution in nursing animals.
医薬品相互作用
Increased risk for serotonin syndrome
May decrease or reverse the effects of SSRIs (acts as a serotonin antagonist)
Fluoxetine may increase diazepam and alprazolam plasma levels
Increased risk for hyponatremia
May alter insulin requirements (can alter blood glucose)
Increased risk for serotonin syndrome
High risk for serotonin syndrome; use contraindicated. A 5-week washout is required after stopping fluoxetine before starting an MAOI, and a 2-week washout if switching from an MAOI to fluoxetine.
Serotonin syndrome-like adverse effects possible
Increased plasma levels of phenytoin possible
Fluoxetine may increase these beta-blocker's plasma levels; atenolol may be safer to use
SSRIs can inhibit the metabolism of tramadol to active metabolites, decreasing efficacy and increasing toxicity risk (serotonin syndrome, seizures)
Fluoxetine may increase TCA blood levels and increase the risk for serotonin syndrome
Increased plasma levels of trazodone possible
Fluoxetine may increase the risk for bleeding
Risk of fatal serotonin syndrome. Fluoxetine should not be used within 2 weeks of MAOI treatment, and MAOIs should not be used within 6 weeks of fluoxetine treatment.
Fluoxetine antagonizes the effects of anticonvulsants and lowers the seizure threshold.
Lowers seizure threshold, increasing the risk of seizures.
Increased risk of bleeding in the case of tissue trauma.
Increased risk of serotonin syndrome. Use alongside trazodone may be considered in exceptional cases only with careful monitoring.
Increased risk of serotonin syndrome.
監視
- Efficacy of the behavior modification plan and reduction of clinical signs
- Appetite and body weight (due to risk of anorexia)
- Signs of adverse effects (GI upset, lethargy, paradoxical aggression, seizures)
- Behavioral response and changes in aggression
- Signs of serotonin syndrome (tremors, agitation, hyperthermia)
- Gastrointestinal tolerance
薬物動態
半減期
吸収
Well absorbed after oral administration. In dogs, ~70% of an oral dose reaches systemic circulation. Food alters the rate, but not the extent, of absorption. Transdermal bioavailability in cats is poor (~10% of oral route).
分布
Widely distributed throughout the body with highest levels in the lungs and liver. CNS concentrations are detected within 1 hour. Highly protein-bound (~95% in humans). Crosses the placenta and enters maternal milk (20-30% of plasma levels).
代謝
Primarily metabolized in the liver to a variety of metabolites, including the active metabolite norfluoxetine.
消失
Both fluoxetine and norfluoxetine are eliminated slowly. Renal impairment does not substantially affect elimination, but liver impairment decreases clearance rates.
過剰投与
The LD50 for rats is 452 mg/kg.
Clinical Signs of Toxicity:
- Dogs: Vomiting, mydriasis (dilated pupils), lethargy, hyperactivity, and seizures. Seizures have been reported at doses twice the highest recommended human dose.
- Cats: Hypersalivation, vomiting, mydriasis, and excessive vocalization.
Treatment:
- Treatment is symptomatic and supportive.
- Gut emptying techniques (emesis, activated charcoal) should be employed if recent and not contraindicated (e.g., patient is seizing or comatose).
- Diazepam is the treatment of choice for controlling seizures.
- Cyproheptadine can be administered as a serotonin antagonist if serotonin syndrome is suspected.
製品
製剤
- Chewable tablets
- Oral capsules
- Oral solution
- Transdermal gel (compounded - note: poor bioavailability in cats)
- Oral tablets: 8 mg, 16 mg, 20 mg, 32 mg, 64 mg
動物用医薬品
- Fluoxetine Chewable Tablets: 8 mg, 16 mg, 32 mg, & 64 mg; Reconcile® (Lilly)
- Reconcile (8 mg, 16 mg, 32 mg, 64 mg chewable tablets)
ヒト用医薬品
- Fluoxetine HCl Oral Tablets: 10 mg, 15 mg & 20 mg
- Fluoxetine HCl Oral Capsules: 10 mg, 20 mg, 40 mg & 90 mg (delayed-release); Prozac®, Sarafem®
- Fluoxetine HCl Oral Solution: 20 mg/5 mL (may contain alcohol, sucrose); Prozac®
- Prozac (10 mg, 20 mg, 60 mg capsules/tablets)
規制ステータス
Veterinary formulation (Reconcile) is licensed within Europe.
POM-V, POM. Monograph notes veterinary formulation is not currently available in the UK, though human generics may be used under the cascade.
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Capsules and tablets should be stored in well-closed containers at room temperature. The oral liquid should be stored in tight, light-resistant containers at room temperature.
飼主向け情報
- 忍耐が鍵です： この薬が十分に効果を発揮するまでには、通常4〜8週間かかります。すぐに効果が見られないからといって、投薬を中止しないでください。
- 行動修正： フルオキセチンは、獣医師が推奨する行動修正およびトレーニングプログラムと併用することで最も効果を発揮します。
- 副作用： 最も一般的な副作用には、無気力、食欲低下、嘔吐、震え、落ち着きのなさ、下痢、過剰な鳴き声などがあります。これらが重度であるか持続する場合は、獣医師に連絡してください。
- 食欲不振： ペットの食欲が落ちた場合は、手から直接食べさせたり、一時的に食事の嗜好性を高めたり（少量のウェットフードや低ナトリウムのスープを加えるなど）してみてください。
- 急に中止しないでください： 獣医師の指示なしにこの薬を突然中止しないでください。離脱症状や行動の再発を引き起こす可能性があります。
- 発作の警告： まれに、この薬を服用中に犬が発作を起こすことがあります。発作が起きた場合は、直ちに獣医師に連絡してください。
- ダニよけ首輪： ダニよけ首輪を使用している場合は獣医師に知らせてください。一部の首輪にはアミトラズが含まれており、フルオキセチンと併用すると危険な薬物相互作用（セロトニン症候群）を引き起こす可能性があります。
- この薬は、子供や他のペットの手の届かない安全な場所に保管してください。
VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。