アトロピン
**アトロピン (Atropine)** は、獣医療において徐脈の治療、眼科検査のための散瞳、および特定の毒物（有機リン系やカーバメート系など）の中毒管理に主に使用される古典的な抗コリン薬です。また、神経筋遮断の拮抗時に抗コリンエステラーゼ薬と併用されます。 > **臨床上の警告：** 麻酔前のルーチンな投与はもはや推奨されていません。心拍数をモニターし、必要に応じて心拍数低下を管理するためにアトロピンを投与することが推奨されます。
作用機序: Atropine competitively **blocks the action of acetylcholine** at **muscarinic receptors** located at the terminal ends of the parasympathetic nervous system. This blockade → reverses parasympathetic effects → produces **mydriasis** (pupil dilation), **tachycardia**, **bronchodilation**, and general inhibition of gastrointestinal function.
動物種別の用量
- Ophthalmic (mydriasis) · 1 drop in the affected eye · topical · q12-24h to cause mydriasis, then once q24-96h to maintain mydriasis
- Bradyarrhythmias · 0.01-0.03 mg/kg i.v. or 0.03-0.04 mg/kg i.m. · IV/IM · PRN · Low doses may exacerbate bradycardia; repetition of the dose will usually promote an increase in heart rate. IM dose can be given to prevent development of bradycardia during administration of potent opioids such as fentanyl.
- Organophosphate poisoning · 0.2-0.5 mg/kg (¼ dose i.v., ¾ i.m., s.c.) to effect; repeat as necessary; or 0.1-0.2 mg/kg (½ i.v., ½ i.m.) then i.m. q6h · IV/IM/SC · PRN or q6h
- Neuromuscular blockade antagonism · 0.04 mg/kg i.v. · IV · PRN · with edrophonium (0.5-1.0 mg/kg)
- Ophthalmic (mydriasis) · 1 drop in the affected eye · topical · q12-24h to cause mydriasis, then once q24-96h to maintain mydriasis
- Bradyarrhythmias · 0.01-0.03 mg/kg i.v. or 0.03-0.04 mg/kg i.m. · IV/IM · PRN · Low doses may exacerbate bradycardia; repetition of the dose will usually promote an increase in heart rate. IM dose can be given to prevent development of bradycardia during administration of potent opioids such as fentanyl.
- Organophosphate poisoning · 0.2-0.5 mg/kg (¼ dose i.v., ¾ i.m., s.c.) to effect; repeat as necessary; or 0.1-0.2 mg/kg (½ i.v., ½ i.m.) then i.m. q6h · IV/IM/SC · PRN or q6h
- Neuromuscular blockade antagonism · 0.04 mg/kg i.v. · IV · PRN · with edrophonium (0.5-1.0 mg/kg)
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Glaucoma
- Lens luxation
- Keratoconjunctivitis sicca (KCS / dry eye)
有害事象
- Sinus tachycardia
- Blurred vision (due to mydriasis)
- Drying of bronchial secretions
- Increased intraocular pressure (IOP)
- Reduced tear production
- Ventricular arrhythmias
- Hypersalivation (especially in cats, due to bitter taste of ophthalmic drops)
- Ileus (rare in small animals)
- Vomiting (rare in small animals)
薬物相互作用
- Bromides, iodides, sodium bicarbonate, alkalis, noradrenaline · Incompatible when mixed together · major
- Antihistamines · May enhance the activity of atropine · moderate
- Pethidine · May enhance the activity of atropine · moderate
- Benzodiazepines · May enhance the activity of atropine · moderate
- Phenothiazines · May enhance the activity of atropine · moderate
- Thiazide diuretics · May enhance the activity of atropine · moderate
- Sympathomimetics · May enhance the activity of atropine · moderate
- Alpha-2 agonists · Combining is not recommended · major
- Amitraz · May aggravate toxicity signs, leading to hypertension and gut stasis · major
- Tricyclic Antidepressants · Additive anticholinergic effects · moderate
- Alpha-2 Agonists (e.g., Dexmedetomidine) · May cause paradoxical hypertension and significantly increased myocardial workload; concurrent use is generally discouraged · major
- Metoclopramide · Atropine antagonizes the prokinetic effects of metoclopramide on the GI tract · moderate
モニタリング
- Heart rate and rhythm (ECG)
- Pupillary light reflex and pupil size
- Intraocular pressure (IOP)
- Tear production (Schirmer Tear Test)
過量投与
Overdose may lead to severe sinus tachycardia, ventricular arrhythmias (which may be treated with lidocaine if severe), extreme mydriasis, severe drying of secretions, and gastrointestinal stasis.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。