トラゾリン

Tolazoline

Tolazoline hydrochloride

α-アドレナリン受容体遮断薬 / 拮抗薬IVIM犬猫鳥馬牛羊ヤギ

別名: Tolazine · Priscoline · Vaso-Dilatan · benzazoline hydrochloride · tolazolinium chloratum

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

4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/secondIV· once

体重— 🐕

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 reversal of xylazine effects	4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second	IV	once	—	🌎 NA

For reversal of xylazine effects: High concentration (100 mg/mL) makes accurate dosing difficult; yohimbine or human-labeled tolazoline (25 mg/mL) may be safer alternatives. Not FDA-approved for dogs.

猫

適応	用量	経路	頻度	期間	地域
For reversal of xylazine effects	4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second	IV	once	—	🌎 NA

For reversal of xylazine effects: High concentration (100 mg/mL) makes accurate dosing difficult; yohimbine or human-labeled tolazoline (25 mg/mL) may be safer alternatives. Not FDA-approved for cats.

鳥

適応	用量	経路	頻度	期間	地域
As a reversal agent for alpha2-adrenergic agonists (e.g., xylazine, detomidine, etc.)	15 mg/kg IV	IV	once	—	🌎 NA

馬

適応	用量	経路	頻度	期間	地域
For reversal of xylazine effects	4 mg/kg slow IV (4 mL/220 lb. of body weight); administration rate should approximate 1 mL/second	IV	once	—	🌎 NA

For reversal of xylazine effects: FDA-approved for use in horses.

牛

適応	用量	経路	頻度	期間	地域
For reversal of xylazine effects	2-4 mg/kg slow IV ; titrate to effect	IV	once	—	🌎 NA
For reversal of xylazine effects (Emergency)	2 mg/kg IM	IM	once	—	🌎 NA

For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.
For reversal of xylazine effects (Emergency): Should not be administered IV rapidly as this can result in cardiac asystole. Effects of reversal should start to become evident about 10 minutes following IM administration.

羊

適応	用量	経路	頻度	期間	地域
For reversal of xylazine effects	2-4 mg/kg slow IV ; titrate to effect	IV	once	—	🌎 NA
For reversal of xylazine effects	1-2 mg /kg IM. Give 50% of initial dose slow IV or IM and then determine if more is needed.	IM/IV	once	—	🌎 NA

For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.

ヤギ

適応	用量	経路	頻度	期間	地域
For reversal of xylazine effects	2-4 mg/kg slow IV ; titrate to effect	IV	once	—	🌎 NA
For reversal of xylazine effects	1-2 mg /kg IM. Give 50% of initial dose slow IV or IM and then determine if more is needed.	IM/IV	once	—	🌎 NA

For reversal of xylazine effects: Slaughter withdrawal: 30 days. Not FDA-approved in the USA for use in food animals.

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。

診察中ですか？VetSheet の AI が薬剤・用量・投与期間を構造化された診察記録に直接記入します。VetSheet の仕組みを見る

概要

トラゾリンは非選択的競合的α-アドレナリン受容体遮断薬であり、獣医学においては主に馬や反芻動物におけるキシラジンの鎮静、鎮痛、および心血管系への作用を拮抗（リバース）するために使用されます。

臨床上のポイント：キシラジンの拮抗には非常に有効ですが、デクスメデトミジンやデトミジンなどの新しい高選択性α2作動薬に対しては、特異性や効果が劣ると考えられています（これらの場合はアチパメゾールが推奨されます）。
α1およびα2受容体の両方を遮断し、直接的な血管拡張作用を持つため、心血管系への影響が複雑で予測困難な場合があり、ゆっくりと慎重に投与する必要があります。

作用機序

Tolazoline acts as a competitive antagonist at both α1- and α2-adrenergic receptors.

Central & Peripheral α2 Blockade → Reverses the sedation, analgesia, and bradycardia induced by α2-agonists (like xylazine).
Direct Smooth Muscle Relaxation → Exerts a direct relaxant effect on vascular smooth muscle → peripheral vasodilation → decreases total peripheral resistance.
Onset: Rapid acting (usually within 5 minutes of IV administration), but has a short duration of action, meaning repeat doses may occasionally be required if re-sedation occurs.

安全性・警告

禁忌

Horses exhibiting signs of stress, debilitation, or shock
Cardiac disease or coronary artery disease
Sympathetic blockage
Hypovolemia
Cerebrovascular disease
Known hypersensitivity to the drug
Foals (relative contraindication; adverse reactions and fatalities reported)

有害事象

Transient tachycardia
Peripheral vasodilation (sweating, injected mucous membranes of gingiva and conjunctiva)
Hyperalgesia of the lips (licking, flipping of lips)
Piloerection
Clear lacrimal and nasal discharge
Muscle fasciculations
Apprehensiveness and anxiety
Gastrointestinal hypermotility (flatulence, diarrhea, mild colic)

注意事項

WARNING: Rapid IV Administration Acute death and cardiac asystole have been reported after rapid IV administration of tolazoline at high dosages, particularly in camelids and cattle. Always administer IV slowly (e.g., 1 mL/second) or consider the IM route.

High Concentration Risk: The veterinary formulation is highly concentrated (100 mg/mL), making accurate dosing difficult in small animals (dogs/cats). Yohimbine or atipamezole are generally safer alternatives for small animals.
Human Safety: Humans with coronary artery or cerebrovascular disease should use extra caution when handling this agent.

医薬品相互作用

Alcohol

Accumulation of acetaldehyde can occur if tolazoline and alcohol are given simultaneously.

Epinephrine

If large doses of tolazoline are given with epinephrine, a paradoxical drop in blood pressure can occur followed by a precipitous increase in blood pressure.

Norepinephrine

If large doses of tolazoline are given with norepinephrine, a paradoxical drop in blood pressure can occur followed by a precipitous increase in blood pressure.

監視

Reversal effects (efficacy of waking up/recovery)
Heart rate and rhythm
Blood pressure
Adverse effects (sweating, GI hypermotility, anxiety)

薬物動態

半減期

馬Approximately 1 hour

吸収

Rapid acting after IV administration (usually within 5 minutes).

分布

Widely distributed. Animal studies have demonstrated that tolazoline is concentrated in the liver and kidneys.

過剰投与

Overdoses can cause severe cardiovascular and gastrointestinal disturbances.

Horses (5X overdose): Gastrointestinal hypermotility resulting in flatulence, defecation, mild colic, and transient diarrhea. Intraventricular conduction may be slowed (prolongation of the QRS-complex). Ventricular arrhythmias and death may occur at higher overdoses.
Camelids (5X overdose in a llama): Anxiety, hyperesthesia, profuse salivation, GI tract hypermotility, diarrhea, convulsions, hypotension, and tachypnea. Successfully treated with IV diazepam, phenylephrine, IV fluids, and oxygen.
Human Treatment Note: Ephedrine (NOT epinephrine or norepinephrine) has been recommended to treat serious tolazoline-induced hypotension.

製品

製剤

Injection: 100 mg/mL (Veterinary)
Injection: 25 mg/mL (Human-labeled, historically)

動物用医薬品

Tolazoline HCl Injection: 100 mg/mL in 100 mL multi-dose vials (Tolazine®)

規制ステータス

規制データなし: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

保管・安定性

Commercially available injection products should be stored between 15-30°C and protected from light. Reportedly physically compatible with commonly used IV solutions.

飼主向け情報

トラゾリンは、処置や検査の後に動物を「目覚めさせる（鎮静剤の拮抗）」ために、獣医療従事者によってのみ投与される薬剤です。

予想されること：動物が目覚める際に、発汗、唇を舐める行動、不安、または筋肉の震えなどの一時的な副作用が見られることがあります。
持続時間：これらの影響は通常軽度であり、投与後2時間以内に減弱し消失するはずです。
安全性：心拍数や血圧の急激な変化が起こる可能性があるため、回復期間中は獣医療チームによって動物が注意深く監視されます。

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。