トラゾドン
Trazodone
Trazodone hydrochloride
別名: Desyrel · Oleptro · Molipaxin · AF-1161 · trazodona · sleepeasy · Trazodone hydrochloride · Trazodonum
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 |
|---|---|---|---|---|---|
| Adjunctive treatment of anxiety-related disorders (Daily medication only) | 1.9 mg/kg/day-16.2 mg/kg/day (mean = 7.3 mg/kg/day) | PO | daily | — | 🌎 NA |
| Adjunctive treatment of anxiety-related disorders (As needed only) | 2.2 mg/kg/day- 14 mg/kg/day (mean 7.7 mg/kg/day) | PO | PRN | — | 🌎 NA |
| Adjunctive treatment of anxiety-related disorders (Daily medication and as needed) | 1.7 mg/kg/day-19.5 mg/kg/day (mean 7.25 mg/kg/day) | PO | daily and PRN | — | 🌎 NA |
| Adjunctive treatment of anxiety-related disorders | 1 mg/kg PO q12h for 7 days, then up to 3 mg/kg PO q12h. | PO | q12h | 7 days initially | 🌎 NA |
| Adjunctive treatment of anxiety-related disorders | 1-4.8 mg/kg PO twice daily; (titrate to effect in 1 mg increments every 7 days). | PO | q12h | — | 🌎 NA |
| Adjunctive treatment of anxiety-related disorders (Situational) | typical starting dose between 2-5 mg/kg and adjusting upwards as necessary to get control (maximum dose 14 mg/kg/day). | PO | PRN | — | 🌎 NA |
- Adjunctive treatment of anxiety-related disorders (Daily medication only): Begin at half target dose for 3 days to build tolerance.
- Adjunctive treatment of anxiety-related disorders (Situational): Given about an hour prior to the onset of anxiety.
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
トラゾドンはセロトニン2A拮抗薬/再取り込み阻害薬 (SARI)であり、獣医療において抗不安薬および軽度の鎮静薬として広く使用されています。
- 臨床的有用性: 状況的不安（雷雨、花火、動物病院への受診、旅行など）や、術後の運動制限・ケージレストの補助に非常に有効です。
- 補助療法: 難治性の行動障害に対して、SSRI（フルオキセチンなど）やガバペンチンと併用されることがよくあります。
- 安全性: 一般的に忍容性が高く、安全域が広いです。三環系抗うつ薬（TCA）と比較して抗コリン作用が少なく、発作のリスクも低いです。
- ヒトでの用途: うつ病、攻撃的行動、アルコールやコカインの離脱症状、片頭痛の予防、不眠症の治療に使用されます。
作用機序
Trazodone exerts its anxiolytic and sedative effects through multiple neurochemical pathways:
- Serotonin Reuptake Inhibition: Blocks the serotonin transporter (SERT) → increases extracellular serotonin (5-HT) in the synaptic cleft.
- 5-HT2A Receptor Antagonism: Blocks 5-HT2A receptors → prevents overstimulation by serotonin, contributing to its anxiolytic and antidepressant efficacy. Downregulation of these receptors can augment the efficacy of concurrent SSRIs.
- Active Metabolite: Hepatic metabolism produces m-chlorophenylpiperazine (mCPP), which acts as a direct, non-selective serotonin receptor agonist.
- Alpha-1 Adrenergic Antagonism: Blocks peripheral alpha-1 receptors → can cause mild vasodilation and hypotension.
- Histamine (H1) Antagonism: Weak blockade of H1 receptors contributes to its sedative properties.
安全性・警告
禁忌
- Hypersensitivity to trazodone
- Concurrent use of MAO inhibitors (e.g., amitraz, selegiline)
- Glaucoma
- History of seizures
- Urinary retention
- Severe liver disease
有害事象
- Sedation
- Lethargy
- Ataxia
- Cardiac conduction disturbances
- Increased anxiety (paradoxical)
- Aggression (paradoxical)
- Vomiting/gagging
- Increased excitement
- Increased appetite
- Colitis
- Serotonin syndrome (rare, usually with concurrent serotonergic drugs)
- Excitability
- Dry mouth
- Third eyelid protrusion (in cats)
注意事項
Cardiac & Organ Impairment: Use with caution in patients with severe cardiac disease or hepatic or renal impairment. Pregnancy: FDA Category C. Animal studies show adverse effects at very high doses (15-50X). Weigh potential risks versus benefits in pregnant or nursing animals. Serotonin Syndrome: Risk increases significantly when combined with other serotonergic drugs (e.g., SSRIs, MAOIs, TCAs).
医薬品相互作用
May increase reductions in blood pressure and cause hypotension
Increase risk for GI bleeding; monitor
May increase trazodone blood levels
Use with trazodone may cause additive CNS depressant effects
Trazodone may increase digoxin levels
May increase trazodone blood levels
Increased risk for serotonin syndrome
Increased risk for GI bleeding; monitor
May increase trazodone blood levels; cause additive CNS effects
Increased risk for serotonin syndrome. Commonly used together, but monitor closely.
Contraindicated; high risk of serotonin syndrome
Metabolized by CYP450 2D6; potential for altered metabolism and toxicity
Metabolized by CYP450 2D6; potential for altered metabolism and toxicity
Increased risk of serotonin syndrome, though adjunctive therapy is sometimes used cautiously
Inhibits the breakdown of trazodone, leading to increased blood levels
Increases the breakdown of trazodone, leading to decreased blood levels
May inhibit the breakdown of trazodone (theoretical risk based on ketoconazole similarity)
監視
- Clinical efficacy (behavioral calming)
- Adverse effects (sedation, GI upset, paradoxical excitement)
- Signs of serotonin syndrome (vomiting, diarrhea, seizures, hyperthermia, hyperesthesia, mydriasis)
- Renal function (in patients with pre-existing renal disease)
- Signs of serotonin syndrome (tremors, agitation, hyperthermia)
- Efficacy of anxiety reduction
薬物動態
吸収
In humans, oral bioavailability of immediate-release tablets is about 65%. Presence of food increases absorption (AUC), decreases Cmax, and delays Tmax.
分布
Approximately 90-95% bound to plasma proteins. Volume of distribution ranges from 0.47-0.84 L/kg (in humans).
代謝
Extensive hepatic metabolism. Oxidative cleavage via CYP3A4 forms the active metabolite m-chlorophenylpiperazine (mCCP), which is further metabolized to inactive compounds via CYP2D6.
消失
Mostly (70-75%) excreted via renal mechanisms (only 0.13% unchanged in urine). About 21% is excreted in feces.
過剰投与
No specific information is available regarding trazodone overdoses in veterinary patients. In humans, the incidence of serious toxicity from trazodone overdose alone is low compared with tricyclic antidepressant overdoses. In the event of a substantial overdose, contact an animal poison control center for guidance. Monitor for profound sedation, ataxia, hypotension, and signs of serotonin syndrome.
製品
製剤
- Oral tablets (immediate-release)
- Oral tablets (extended-release)
- 100 mg tablets
- 150 mg tablets
- 100 mg capsules
- 150 mg capsules
- 10 mg/ml oral liquid
ヒト用医薬品
- Trazodone Oral Tablets: 50 mg, 100 mg, 150 mg, & 300 mg; generic; (Rx)
- Trazodone Extended-Release (24-hour) Oral Tablets: 150 mg & 300 mg; Oleptro® (Labopharm); (Rx)
- Desyrel
- Molipaxin
規制ステータス
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Store between 20-25°C (68-77°F); excursions are permitted to 15-30°C (59-86°F). Keep in an airtight container and protect from light.
飼主向け情報
- 投与方法: 胃腸の不調（嘔吐や吐き気など）を最小限に抑えるため、食事と一緒に与えることをお勧めします。
- タイミング: 状況的不安（動物病院への受診、花火など）に対しては、ストレスのかかる出来事の1〜2時間前に投与してください。
- 観察: ペットに過度の鎮静、無気力、またはふらつき（運動失調）が見られないか観察してください。
- 逆説的反応: まれに、興奮の増加、不安、食欲の変化を示すことがあります。
- 重要な警告: 獣医師の指示なしに、他の薬やサプリメント（特にアミトラズを含むダニよけ首輪）と併用しないでください。まれに重篤なセロトニン症候群を引き起こす可能性があります。
- 報告: トラゾドンの犬への広範な使用はまだ研究段階であるため、予期せぬ副作用が見られた場合は獣医師に報告してください。
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。