硫酸アトロピン

Atropine Sulfate

dl-hyoscyamine (racemic mixture of d-hyoscyamine and l-hyoscyamine)

抗コリン薬 / 抗ムスカリン薬IVIMSCPOIOIntratracheal (IT)Inhalation犬猫小型哺乳類フェレット鳥爬虫類馬牛豚羊ヤギ

別名: Atroject · Atropine SA · Atropine L.A. · AtroPen · Sal-Tropine · dl-hyoscyamine · atrop. sulph. · atropine sulphate · atropini sulfas

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

0.01-0.02 mg/kgIM, IV· 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
As a preanesthetic adjuvant (geriatric patients)	0.01-0.02 mg/kg	IM, IV	once	—	🌎 NA
As a preanesthetic adjuvant	0.074 mg/kg	IV, IM or SC	once	—	🌎 NA
As a preanesthetic adjuvant	0.02-0.04 mg/kg	SC, IM or IV	once	—	🌎 NA
During cardiopulmonary cerebral resuscitation (CPCR) efforts	0.04 mg/kg (IV or IO); 0.08-0.1 mg/kg (IT)	IV, IO, IT	every 3-5 minutes	maximum of 3 doses	🌎 NA
Adjunctive treatment of bradycardias, Incomplete AV block, etc.	0.02-0.04 mg/kg	IV or IM	as needed	—	🌎 NA
Atropine Response Test (Rishniw Preference)	0.04 mg/kg	IV	once	—	🌎 NA
Atropine Response Test (Kittleson Preference)	0.04 mg/kg	SQ	once	—	🌎 NA
Treatment of cholinergic toxicity	0.2-0.5 mg/kg	IV, IM, SC	as needed	—	🌎 NA
Treatment of bronchoconstriction	0.02-0.04 mg/kg	parenteral	as needed	duration of effect 1-1.5 hours	🌎 NA

As a preanesthetic adjuvant (geriatric patients): Do not use anticholinergics indiscriminately in geriatric patients.
During cardiopulmonary cerebral resuscitation (CPCR) efforts: For IT administration: dilute in 5-10 mL of sterile water before administering.
Atropine Response Test (Rishniw Preference): Wait 15 minutes, record ECG. Persistent sinus tachycardia at >140 bpm expected in vagally-mediated bradycardia.
Atropine Response Test (Kittleson Preference): Wait 30 minutes, record ECG. Persistent sinus tachycardia at >140 bpm expected in vagally-mediated bradycardia.
Treatment of cholinergic toxicity: 1/4 of the dose IV and the remainder IM or SC

猫

適応	用量	経路	頻度	期間	地域
As a preanesthetic adjuvant (geriatric patients)	0.01-0.02 mg/kg	IM, IV	once	—	🌎 NA
As a preanesthetic adjuvant	0.074 mg/kg	IV, IM or SC	once	—	🌎 NA
As a preanesthetic adjuvant	0.02-0.04 mg/kg	SC, IM or IV	once	—	🌎 NA
During cardiopulmonary cerebral resuscitation (CPCR) efforts	0.04 mg/kg (IV or IO); 0.08-0.1 mg/kg (IT)	IV, IO, IT	every 3-5 minutes	maximum of 3 doses	🌎 NA
Treatment of bradycardias	0.02-0.04 mg/kg	SC, IM or IV	q4-6h	—	🌎 NA
Treatment of cholinergic toxicity	0.2-2 mg/kg	IV, SC, IM	as needed	—	🌎 NA

As a preanesthetic adjuvant (geriatric patients): Do not use anticholinergics indiscriminately in geriatric patients.
During cardiopulmonary cerebral resuscitation (CPCR) efforts: For IT administration: dilute in 5-10 mL of sterile water before administering.
Treatment of cholinergic toxicity: give 1/4th of the dose IV and the remainder SC or IM

小型哺乳類

適応	用量	経路	頻度	期間	地域
To treat organophosphate toxicity (Rabbits/Rodents)	10 mg/kg	SC	q20 minutes	—	🌎 NA

フェレット

適応	用量	経路	頻度	期間	地域
As a premed	0.05 mg/kg	SC or IM	once	—	🌎 NA

鳥

適応	用量	経路	頻度	期間	地域
Organophosphate poisoning	0.2 mg/kg	IM	every 3-4 hours as needed	—	🌎 NA
To assist in diagnosing organophosphate poisoning	0.02 mg/kg	IV	once	—	🌎 NA
As a preanesthetic	0.04-0.1 mg/kg	IM or SC	once	—	🌎 NA

Organophosphate poisoning: 1/4th the initial dose is administered. Use with pralidoxime (not in raptors) at 10-20 mg/kg IM q8-12h as needed.
To assist in diagnosing organophosphate poisoning: If bradycardia does not reverse, may consider organophosphate toxicity.

爬虫類

適応	用量	経路	頻度	期間	地域
Organophosphate toxicity in most species	0.1-0.2 mg/kg	SC or IM	as needed	—	🌎 NA
Ptyalism in tortoises	0.05 mg/kg (50 micrograms/kg)	SC or IM	once daily	—	🌎 NA

馬

適応	用量	経路	頻度	期間	地域
Treatment of bradyarrhythmias due to increased parasympathetic tone	0.01-0.02 mg/kg	IV	as needed	—	🌎 NA
Treatment of bradyarrhythmias due to increased parasympathetic tone	0.045 mg/kg	parenterally	as needed	—	🌎 NA
As a bronchodilator	5 mg	IV	once	—	🌎 NA
As a bronchodilator (rescue medication for severe airway obstruction)	5-7 mg/kg	IV	single rescue dose	—	🌎 NA
Organophosphate poisoning	Approximately 1 mg/kg	IV, SC	may repeat every 1.5-2 hours as required subcutaneously	—	🌎 NA
Organophosphate poisoning	0.22 mg/kg	IV, SC, IM	as needed	—	🌎 NA

As a bronchodilator: for a 400-500 kg animal
As a bronchodilator (rescue medication for severe airway obstruction): for a 450 kg horse. Abbreviated duration (0.5-2 hours). Adverse effects limit use to a single rescue dose.
Organophosphate poisoning: given to effect, IV (use mydriasis and absence of salivation as therapy endpoints)
Organophosphate poisoning: 1/4th of the dose administered IV and the remainder SC or IM

牛

適応	用量	経路	頻度	期間	地域
As a preanesthetic	0.06-0.12 mg/kg	IM	once	—	🌎 NA
Adjunctive treatment of bovine hypersensitivity disease	1 gram per cow once daily followed by 0.5 gram/cow in 2-3 days	not specified	once daily then in 2-3 days	2-3 days	🌎 NA
Treatment of cholinergic toxicity (organophosphates)	0.5 mg/kg (average dose)	IV, SC, IM	may repeat q3-4h	1-2 days	🌎 NA

As a preanesthetic: Not used routinely as a preoperative agent in ruminants due to lack of extended efficacy and potential adverse reactions.
Treatment of cholinergic toxicity (organophosphates): give 1/4th of the dose IV and the remainder SC or IM

豚

適応	用量	経路	頻度	期間	地域
Organophosphate toxicity	Use equine dose	IV, SC, IM	as needed	—	🌎 NA
As an adjunctive preanesthetic agent	0.04 mg/kg	IM	once	—	🌎 NA

羊

適応	用量	経路	頻度	期間	地域
Treating organophosphate toxicity	Use the dose for cattle	IV, SC, IM	as needed	—	🌎 NA

ヤギ

適応	用量	経路	頻度	期間	地域
Treating organophosphate toxicity	Use the dose for cattle	IV, SC, IM	as needed	—	🌎 NA

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。

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概要

硫酸アトロピンは天然のベラドンナアルカロイドであり、獣医療で広く使用される抗ムスカリン（抗コリン）薬のプロトタイプです。

主な臨床応用は以下の通りです：

救急医療および心肺脳蘇生（CPCR）：血行動態的に有意な洞性徐脈、洞房ブロック、および不完全房室ブロックの治療。
麻酔：気道および唾液の分泌を予防または減少させ、迷走神経性の徐脈を軽減するための麻酔前投薬として使用。
毒物学：コリン作動薬（有機リン、カーバメート、ムスカリン含有キノコ、アオコ中毒など）の過剰摂取に対する救命解毒剤。
呼吸器系：気管支収縮性疾患の補助治療。

臨床のポイント：アトロピンは非常に有効ですが、ルーチンの麻酔前投薬プロトコルでの使用は減少しつつあり、ターゲットを絞った使用や、血液脳関門を通過しにくく作用時間が長いグリコピロレートなどの代替薬が好まれる傾向にあります。

作用機序

Atropine acts as a competitive, reversible antagonist at muscarinic acetylcholine receptors (mAChRs) (M1-M5 subtypes) located at postganglionic parasympathetic neuroeffector sites.

By blocking acetylcholine (ACh) binding, it inhibits parasympathetic tone:

Cardiovascular: Blocks vagal tone at the SA and AV nodes → increases heart rate (positive chronotropy) and improves AV conduction (positive dromotropy).
Secretions: Inhibits glandular M3 receptors → decreases salivary, bronchial, and gastric secretions.
Smooth Muscle: Relaxes smooth muscle in the GI, urinary, and biliary tracts → decreases motility and spasm.
Ocular: Blocks M3 receptors in the pupillary sphincter and ciliary muscle → causes pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).

Mechanistic Note: At very low doses, atropine can cause a paradoxical, transient bradycardia due to the blockade of presynaptic M1 autoreceptors on vagal postganglionic fibers, which normally inhibit ACh release. High doses may also block nicotinic receptors at autonomic ganglia and the neuromuscular junction.

安全性・警告

禁忌

Narrow-angle glaucoma
Synechiae (adhesions) between the iris and lens
Hypersensitivity to anticholinergic drugs
Tachycardias secondary to thyrotoxicosis or cardiac insufficiency
Myocardial ischemia
Unstable cardiac status during acute hemorrhage
GI obstructive disease or paralytic ileus
Severe ulcerative colitis
Obstructive uropathy
Myasthenia gravis (unless used to reverse adverse muscarinic effects secondary to therapy)

有害事象

Dry mouth (xerostomia)
Dysphagia
Constipation
Vomiting
Thirst
Urinary retention or hesitancy
CNS stimulation, drowsiness, ataxia, seizures, respiratory depression
Blurred vision, pupil dilation (mydriasis), cycloplegia, photophobia
Sinus tachycardia (at higher doses)
Paradoxical bradycardia (initially or at very low doses)
Hypertension or hypotension
Arrhythmias (ectopic complexes)
Decreased gut motility (can induce colic in horses or rumen stasis in cattle)

注意事項

General Precautions:

Use with extreme caution in patients with known or suspected GI infections; decreased motility can prolong retention of causative agents or toxins.
Use with extreme caution in patients with autonomic neuropathy.
Use cautiously in patients with hepatic or renal disease, geriatric or pediatric patients, hyperthyroidism, hypertension, CHF, tachyarrhythmias, prostatic hypertrophy, or esophageal reflux.

Species-Specific Warnings:

Neonates: Reportedly not effective in treating bradycardias in puppies <14 days old or kittens <11 days old. May damage hypoxic myocardia in neonates.
Rabbits: Glycopyrrolate is preferred, as ~40% of rabbits possess endogenous atropinesterase, rendering atropine ineffective.
Horses: Systemic use may decrease gut motility and induce colic. May reduce arrhythmogenic doses of epinephrine.
Cattle: May result in inappetence and rumen stasis persisting for several days.
Food Animals: FARAD recommends a 28-day meat and 6-day milk withdrawal time when used at doses up to 0.2 mg/kg.