アルプラゾラム
Alprazolam
別名: Xanax XR · Niravam · Alprazolam Intensol · D65 MT · U 31889 · alprazolamum
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 |
|---|---|---|---|---|---|
| For treatment of canine anxiety disorders | 0.01-0.1 mg/kg PO as needed for panic, not to exceed 4 mg/dog/day. Start with 1-2 mg (total dose) for a medium-sized dog. | PO | prn | — | 🌎 NA |
| For separation anxiety | 0.25 mg-2 mg (total dose) once daily to three times daily PO. | PO | q8-24h | — | 🌎 NA |
| For storm phobias | 0.02-0.4 mg/kg PO q4h as needed | PO | q4h | — | 🌎 NA |
| For storm phobias (adjunct) | 0.02 mg/kg PO as needed one hour before anticipated storm and every 4 hours as needed | PO | q4h | — | 🌎 NA |
| For phobias, night waking | 0.01-0.1 mg/kg or 0.25-2 mg (total dose) per dog PO q6-12h PO | PO | q6-12h | — | 🌎 NA |
| For acute anxiety | 0.05-0.1 mg/kg PO prn or three times a day. Administer 30-60 minutes prior to trigger event. | PO | prn or q8h | — | 🌎 NA |
| Anxiolysis and fear-related disorders | 0.01-0.1 mg/kg | PO | prn up to q6h | As needed | 🌍 EU |
- For storm phobias: Helps to minimize impact of experiencing a severe storm
- For storm phobias (adjunct): Used as an adjunct after behavior modification and prior clomipramine treatment
- Anxiolysis and fear-related disorders: Titrate up or down to the minimum effective dose. Best given ~30 mins before a fear-inducing event.
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| For treatment of feline anxiety disorders | 0.125-0.25 mg/kg PO q12h (Start at 0.125 mg/kg PO) | PO | q12h | — | 🌎 NA |
| For refractory house soiling | 0.1 mg/kg or 0.125-0.25 mg (total dose) per cat PO q8-12h | PO | q8-12h | — | 🌎 NA |
| For urine marking | 0.05-0.2 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| For fears/phobias/anxieties | 0.125-0.25 mg (total dose) PO once to three times a day. | PO | q8-24h | — | 🌎 NA |
| For acute anxiety | 0.05 mg/kg PO prn or three times a day. Administer 30-60 minutes prior to trigger event. | PO | prn or q8h | — | 🌎 NA |
| Anxiolysis and urine spraying | 0.125-0.25 mg/kg | PO | prn up to bid | As needed | 🌍 EU |
- Anxiolysis and urine spraying: Doses as low as 0.25 mg/cat q8-12h and as high as 0.6 mg/kg have been reported. Titrate down to minimum effective dose. High relapse rate for urine spraying upon withdrawal.
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
アルプラゾラムは、強力で短〜中時間作用型のベンゾジアゼピン系薬物であり、獣医学では主に抗不安薬および軽度の鎮静薬として使用されます。スケジュールIV（C-IV）の規制薬物です。
主な臨床的特徴：
- 行動修正：パニック障害、雷恐怖症、分離不安、不適切な排泄（猫の尿マーキングなど）の補助療法として頻繁に処方されます。
- 運動機能：ジアゼパムと比較して、低用量では運動機能への悪影響が少ない可能性があり、歩行可能な患者に適しています。
- 臨床のポイント：脂溶性が高いため経口投与後の効果発現が早く、引き金となる出来事の30〜60分前に投与すれば、状況的恐怖（雷雨や花火など）に非常に有効です。
作用機序
Alprazolam exerts its effects by binding to specific benzodiazepine receptors located on the GABA-A receptor complex in the central nervous system.
- Mechanism: Binding → enhances the affinity of the receptor for gamma-aminobutyric acid (GABA) → increases the frequency of chloride channel opening → cellular hyperpolarization → decreased neuronal excitability.
- Target Areas: It primarily depresses subcortical levels of the CNS, specifically the limbic system, thalamus, and hypothalamus.
- Net Effect: This enhanced inhibitory neurotransmission produces the characteristic anxiolytic, sedative, skeletal muscle relaxant, and anticonvulsant effects.
安全性・警告
禁忌
- Known benzodiazepine hypersensitivity
- Aggressive animals (controversial; anxiety reduction may disinhibit aggressive tendencies)
有害事象
- Sedation
- Increased appetite (polyphagia)
- Transient ataxia
- Behavior changes in cats (irritability, increased affection, depression, aberrant demeanor)
- Paradoxical CNS excitement/agitation (rare in dogs)
- Physical dependence (with chronic use)
- Impeded learning and retarded training
注意事項
Caution: Use with care in patients with hepatic or renal disease, narrow-angle glaucoma, and in debilitated or geriatric patients.
- Working Animals: Benzodiazepines may impair the abilities of working or service animals.
- Aggression: Use in aggressive dogs remains controversial as it may remove anxiety-based bite inhibition.
- Pregnancy: FDA Category D in humans. May cause congenital abnormalities if administered during the first trimester. Use only when benefits clearly outweigh risks.
- Hepatic Function: Monitor hepatic enzymes, particularly in cats receiving chronic therapy, due to the risk of idiosyncratic hepatotoxicity associated with some oral benzodiazepines.
医薬品相互作用
May slow the rate, but not the extent of oral absorption of alprazolam; administer 2 hours apart.
Additive CNS depression effects may occur.
Serum levels of digoxin may be increased; monitor for toxicity.
Increased alprazolam levels.
Metabolism of alprazolam may be decreased, leading to excessive sedation.
May induce hepatic microsomal enzymes and decrease the pharmacologic effects of benzodiazepines.
Alprazolam may increase levels of these drugs; concurrent use with clomipramine may improve efficacy for phobias.
Inhibits alprazolam metabolism, potentially increasing sedation and toxicity
Inhibits alprazolam metabolism
Used concurrently as an adjunct, but may have additive CNS depressant effects
監視
- Clinical efficacy (reduction in anxiety/panic)
- Adverse effects (excessive sedation, paradoxical excitation)
- Hepatic enzymes (particularly when treating cats chronically)
薬物動態
吸収
Well absorbed orally with an intermediate onset of action. Peak plasma levels occur in 1-2 hours (in humans).
分布
Highly lipid soluble and widely distributed throughout the body. Readily crosses the blood-brain barrier. Approximately 80% bound to plasma proteins.
代謝
Metabolized in the liver to at least two metabolites, including alpha-hydroxy-alprazolam which is pharmacologically active.
消失
Elimination half-lives range from 6-27 hours in humans.
過剰投与
Overdoses are generally limited to CNS signs, primarily dose-dependent CNS depression.
- Clinical Signs: Ataxia, lethargy, disorientation, and vomiting. Some animals may present with a paradoxical reaction (hyperactivity, vocalization, agitation) which may be followed by CNS depression. Severe signs like hypotension, respiratory depression, and cardiac arrest are quite rare in small animals.
- Toxicity: The reported LD50 in rats is >330 mg/kg, but cardiac arrest has occurred at doses as low as 195 mg/kg.
- Treatment: Consists of standard protocols for decontamination. The decision to give activated charcoal should be weighed carefully against the risk of aspiration if the patient is sedated. Flumazenil can be used to reverse the sedative effects, but is generally reserved for cases with significant CNS and respiratory depression.
製品
製剤
- Extended-release oral tablets
- Orally disintegrating tablets
- Oral solution
ヒト用医薬品
- Alprazolam Oral Tablets: 0.25 mg, 0.5 mg, 1 mg & 2 mg (Xanax, generic)
- Alprazolam Extended-release Oral Tablets: 0.5 mg, 1 mg, 2 mg, & 3 mg (Xanax XR, generic)
- Alprazolam Orally Disintegrating Tablets: 0.25 mg, 0.5 mg, 1 mg, & 2 mg (Niravam)
- Alprazolam Oral Solution: 1 mg/mL in 30 mL (Alprazolam Intensol)
規制ステータス
POM (Prescription Only Medicine). Subject to controlled drug regulations depending on member state.
POM. Controlled drug.
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Store tablets at room temperature in tight, light-resistant containers. Orally disintegrating tablets must be protected from moisture. Compounded oral suspensions (1 mg/mL in Ora-Plus/Ora-Sweet) retain >90% potency for 60 days at 5°C and 25°C, but should be protected from light.
飼主向け情報
- タイミングが重要です：状況的な不安（雷雨や花火など）に対しては、ペットがパニックになる前に効果を発揮させるため、予想される出来事の約30〜60分前に投薬してください。
- 投薬方法：錠剤を飲ませるのが難しい場合は、口腔内崩壊錠が選択肢になることがあります。薬を扱う前には、必ず手を完全に乾かしてください。
- 注意すべき症状：過度の眠気、ひどいふらつき、または白目や歯茎の黄染（黄疸）が見られた場合（特に猫）、獣医師に連絡してください。
- 行動の変化：ペットによっては、異常に甘えたり、怒りっぽくなったり、あるいは逆に活発になったりする（奇異反応）ことがあります。このような症状が見られた場合は獣医師にお知らせください。
- トレーニングへの影響：この薬は、トレーニング中の新しいコマンドを学習する能力を一時的に低下させる可能性があります。
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。