キシラジン
Xylazine
Xylazine hydrochloride
別名: Rompun · AnaSed · Sedazine · Cervizine · Chanazine · Gemini · Nerfasin · Sedaxylan · Virbaxyl · Xylacare · Xylapan · Xylazine HCl · Bay-Va-1470 · Xylazine 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
監査済み v13 用量エビデンス
確認済み・計算対象外のエビデンス確認済み・計算対象外のエビデンス (2)
エビデンス表示のみ（自動計算対象外）
Preanesthetic agent (extra-label)
Preanesthetic agent (extra-label): 0.2 – 1 mg/kg IV, IM, or SC 20
必ず考慮する臨床コンテキスト (3)
- NOTE: A reversal agent should always be on hand; reversal of sedative effects also reverses analgesic effects.
- NOTE: Most clinicians prefer using newer alpha-2 agonists (eg, dexmedetomidine) that have a greater selectivity for the alpha-2 adrenergic receptor.
- Do not store above 30°C (86°F). Some manufacturers state to store at 20°C to 25°C (68°F-77°F) and permit excursions up to 40°C (104°F).
エビデンス表示のみ（自動計算対象外）
Analgesic adjunct (extra-label)
Analgesic adjunct (extra-label): 0.05 – 0.5 mg/kg IV, IM, or SC
必ず考慮する臨床コンテキスト (3)
- NOTE: A reversal agent should always be on hand; reversal of sedative effects also reverses analgesic effects.
- NOTE: Most clinicians prefer using newer alpha-2 agonists (eg, dexmedetomidine) that have a greater selectivity for the alpha-2 adrenergic receptor.
- Do not store above 30°C (86°F). Some manufacturers state to store at 20°C to 25°C (68°F-77°F) and permit excursions up to 40°C (104°F).
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
キシラジンは強力なα2アドレナリン受容体作動薬であり、獣医学において鎮静、鎮痛、筋弛緩薬として広く使用されています。また、猫における確実な催吐薬（嘔吐を誘発する薬）としても頻繁に利用されます。
臨床のポイント: キシラジンに対する感受性には著しい種差があります。反芻動物は極めて感受性が高く、馬と同じ効果を得るために必要な用量は約10分の1です。逆に、豚は耐性が高く、反芻動物の20〜30倍の用量を必要とします。
優れた内臓鎮痛効果（特に馬において）を提供しますが、徐脈、不整脈、心拍出量の減少など、心血管系に対する顕著な抑制作用があるため、小動物での使用は通常、若くて健康な患者に限られます。食用動物への使用はFDAによって承認されていませんが、厳格な休薬期間を設けた上で適応外使用されることがあります。
作用機序
Xylazine stimulates presynaptic and postsynaptic alpha-2 adrenergic receptors in the central and peripheral nervous systems.
- Sedation & Analgesia: Activation of central alpha-2 receptors → decreased release of norepinephrine and dopamine → profound CNS depression and analgesia.
- Muscle Relaxation: Centrally mediated inhibition of intraneuronal transmission of impulses in the CNS.
- Cardiovascular Effects (Biphasic): Initial stimulation of peripheral alpha-1 and alpha-2 receptors → transient vasoconstriction and hypertension → subsequent central sympatholytic effect → hypotension, bradycardia, and potentially second-degree AV block. Cardiac output can decrease by up to 30%.
- Emesis: Stimulates the chemoreceptor trigger zone (CRTZ), particularly in cats.
- Endocrine/Renal: Decreases insulin release → transient hyperglycemia. Decreases ADH production → polyuria (especially in ruminants).
安全性・警告
禁忌
- Animals receiving epinephrine
- Active ventricular arrhythmias
- Preexisting cardiac dysfunction
- Hypotension or shock
- Respiratory dysfunction
- Severe hepatic or renal insufficiency
- Preexisting seizure disorders
- Severely debilitated animals
- Last trimester of pregnancy (particularly in cattle)
- Dehydrated or debilitated ruminants
- Urinary tract obstruction (ruminants)
- Intra-arterial injection (may cause severe seizures and collapse)
- Cardiovascular disease
- Systemic disease affecting cardiovascular performance
- Geriatric patients
- Pregnant animals
- Diabetic animals
- Patients receiving sympathomimetic amines
- Conditions where vomiting is contraindicated (e.g., foreign body, raised intraocular pressure)
- Ingestion of strong acids, alkalis, or volatile/oily organic products
- Unconscious or seizing animals, or those with a reduced cough reflex
有害事象
- Emesis (especially in cats, occasionally dogs)
- Muscle tremors
- Bradycardia with partial A-V block
- Reduced respiratory rate and tidal volume
- Sudden movement or kicking in response to sharp auditory stimuli (especially horses)
- Increased urination (cats, cattle)
- Bloat from aerophagia (dogs, cattle)
- Sweating (horses)
- Salivation, ruminal atony, regurgitation, and diarrhea (cattle)
- Premature parturition (cattle)
- Transient hypertension followed by hypotension
- Decreased mucociliary clearance (horses)
- Cardiovascular depression (bradycardia, arrhythmias)
- Vomiting (especially in cats)
- Diuresis (suppression of ADH secretion)
- Transient hyperglycaemia (decreased insulin secretion)
- Mydriasis
- Decreased intraocular pressure
- Increased uterine motility
注意事項
Use extreme caution in ruminants due to high sensitivity; ensure correct product concentration (20 mg/mL vs 100 mg/mL). Horses may appear deeply sedated but can still kick violently in response to sudden noises (auditory stimuli). May induce premature parturition in cattle. Can inhibit GI motility; use cautiously in patients with intestinal impactions. Use cautiously in horses during the vasoconstrictive phase of laminitis. Brachycephalic dogs and horses with upper airway disease may develop dyspnea.
医薬品相互作用
Potential for additive hypotensive effects; use cautiously in animals susceptible to hemodynamic complications.
Prolonged sedation and gastrointestinal stasis possible.
Additive CNS depression. Dosages of these agents may need to be reduced.
May induce the development of ventricular arrhythmias (with or without concurrent halothane).
May cause colic-like clinical signs in horses; concurrent use should be avoided.
Significantly reduces the dose of all other anaesthetic agents required to maintain anaesthesia.
Increased risk of severe cardiac arrhythmias.
監視
- Level of anesthesia/analgesia
- Respiratory function (rate, depth, tidal volume)
- Cardiovascular status (heart rate, rhythm, blood pressure)
- Hydration status (especially if polyuria is present)
- Heart rate and rhythm (ECG)
- Respiratory rate and depth
- Blood glucose (in susceptible patients)
薬物動態
半減期
吸収
Rapid following IM injection, but bioavailabilities are incomplete and variable (40-48% in horses, 17-73% in sheep, and 52-90% in dogs).
分布
Widely distributed; crosses the blood-brain barrier to exert central effects.
代謝
Undergoes hepatic metabolism.
消失
Metabolites are excreted primarily in the urine. Not detected in milk of lactating dairy cattle at 5 and 21 hours post-dose.
過剰投与
In the event of an accidental overdosage, profound CNS and respiratory depression, hypotension, and cardiac arrhythmias may occur. Seizures have also been reported.
- Reversal Agents: Alpha-2 antagonists such as yohimbine, atipamezole, and tolazoline can be used alone or in combination to reverse the effects of xylazine and speed recovery times.
- Supportive Care: Mechanical respiratory support and respiratory stimulants (e.g., doxapram) may be required to treat severe respiratory depressant effects.
製品
製剤
- Injection: 20 mg/mL
- Injection: 100 mg/mL
- Injection: 300 mg/mL (for deer and elk)
- Injectable: 20 mg/ml solution
動物用医薬品
- Xylazine Injection: 20 mg/mL in 20 mL vials
- Xylazine Injection: 100 mg/mL in 50 mL vials
- Xylazine Injection: 300 mg/mL (Cervizine, for deer and elk)
- Chanazine 20 mg/ml solution for injection
- Nerfasin 20 mg/ml solution for injection
- Rompun 20 mg/ml solution for injection
- Sedaxylan 20 mg/ml solution for injection
- Virbaxyl 20 mg/ml solution for injection
- Xylacare 20 mg/ml solution for injection
- Xylapan 20 mg/ml solution for injection
規制ステータス
POM-V
POM-V
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Do not store above 30°C (86°F). Reportedly physically compatible in the same syringe with acepromazine, buprenorphine, butorphanol, chloral hydrate, and meperidine. Compounded mixtures of ketamine, acepromazine, and xylazine ('KAX') are stable for at least 180 days if stored at room temperature in the dark.
飼主向け情報
キシラジンは、処置のために動物を落ち着かせたり、麻酔プロトコルの一部として使用される強力な鎮静・鎮痛薬です。
- 嘔吐: 猫（および時折犬）がこの薬を投与された直後に嘔吐することは非常に一般的です。これは予期される効果であり、場合によってはこの薬を投与する主な理由（例：ペットが毒物を食べた場合など）でもあります。
- 回復: 処置後数時間は、ペットがふらついたり、協調運動ができなくなったり、眠たそうにすることがあります。完全に目覚めるまでは、静かで安全、かつ快適な環境に置いてあげてください。
- 驚愕反射: 動物（特に馬）が深く眠っているように見えても、突然の大きな音によって驚いたり、激しく蹴ったりすることがあります。鎮静状態の動物の周囲では常に静かに行動してください。
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。