アポモルヒネ
アポモルヒネは合成オピオイド誘導体ですが、モルヒネとは異なり顕著な鎮痛作用はありません。獣医療において、誤飲した毒物を迅速に除去するための**犬の第一選択の催吐薬**として広く認識されています。 * **即効性：** 非経口（静脈内/筋肉内）または結膜嚢への点眼により、非常に迅速に嘔吐を誘発します。 * **動物種特異性：** 犬に対して非常に有効です。猫への使用は効果が低く、安全性の懸念があるため議論があり、一般的には推奨されません。 * **制限事項：** 他の催吐薬と同様に、通常は胃内容物の40〜60％（最大80％）しか除去できません。催吐に成功しても、その後の毒物学的モニタリングや治療（活性炭の投与など）が不要になるわけではありません。
作用機序: Apomorphine acts as a **non-selective dopamine agonist**. It directly stimulates **D2-dopaminergic receptors** in the **chemoreceptor trigger zone (CRTZ)** located in the area postrema of the medulla oblongata. **Mechanism Pathway:** Apomorphine administration → Crosses the blood-brain barrier → Stimulates D2 receptors in the CRTZ → Activates the central vomiting center → Initiates the emetic reflex. > **Clinical Pearl:** The CRTZ in dogs is highly sensitive to dopamine, making apomorphine highly effective. In contrast, the feline CRTZ is mediated primarily by alpha-2 adrenergic receptors, which is why alpha-2 agonists (like xylazine or dexmedetomidine) are the preferred emetics for cats, while apomorphine is often ineffective.
動物種別の用量
- Induction of emesis · 0.03 mg/kg IV or 0.04 mg/kg IM (IV route preferred); alternatively a portion of tablet may be crushed in a syringe, dissolved with few drops of water and administered into the conjunctival sac. After sufficient vomiting occurs, rinse conjunctival sac free of unabsorbed apomorphine. · IV/IM/Topical · Once · IV route preferred.
- Induction of emesis · 0.04 mg/kg IV or 0.08 mg/kg IM or SC · IV/IM/SC · Once
- Induction of emesis · 0.04 mg/kg IV, 0.07 mg/kg IM, or 0.25 mg/kg into the conjunctival sac · IV/IM/Topical · Once
- Induction of emesis · 0.2 mg/kg · SC · single dose · single dose · Authorized dose. Do not repeat if ineffective.
- Induction of emesis · 20-40 μg/kg · IV · single dose · single dose · Non-authorized dose and route but some evidence suggests it is at least as effective.
- Induction of emesis · 0.04 mg/kg IV or 0.08 mg/kg IM or SC · IV/IM/SC · Once · Use of apomorphine in cats is controversial and many recommend not using in this species.
- Induction of emesis · Not recommended · IM · single dose · single dose · Xylazine is a potent emetic in cats and at least as safe.
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
- Rodents and rabbits (unable to vomit or lack stomach wall strength)
- Hypoxia, dyspnea, or shock
- Lack of normal pharyngeal reflexes (risk of aspiration)
- Seizuring, comatose, or severely CNS-depressed patients
- Patients who have already vomited repeatedly
- Ingestion of strong acids, alkalis, or other caustic agents (risk of esophageal/gastric rupture)
- Ingestion of petroleum distillates (unless toxicity risk outweighs aspiration risk)
- Ingestion of strychnine or other CNS stimulants (may precipitate seizures)
- Oral opiate or other CNS depressant (e.g., barbiturates) toxicity
- Hypersensitivity to morphine
有害事象
- Protracted vomiting
- CNS depression (lethargy, sedation)
- CNS stimulation (excitement, restlessness)
- Respiratory depression
- Corneal ulcers (anecdotal, associated with conjunctival administration)
薬物相互作用
- Antidopaminergic drugs (e.g., phenothiazines, metoclopramide) · May negate the emetic effects of apomorphine by blocking dopamine receptors in the CRTZ.
- Ondansetron · May cause severe hypotension; concurrent use is contraindicated in humans.
- Opiates or CNS/Respiratory depressants (e.g., barbiturates) · Additive CNS or respiratory depression may occur.
- Antidopaminergics (e.g., phenothiazines) · May reduce the emetic effects of apomorphine · moderate
- Opiates and CNS depressants · Additive CNS or respiratory depression · major
モニタリング
- CNS status (depression or excitement)
- Respiratory rate and effort
- Heart rate and rhythm
- Vomitus (quantify volume, examine for toxic contents, and save for possible later analysis)
過量投与
Excessive doses of apomorphine may result in: * Respiratory and/or cardiac depression * CNS stimulation (excitement, seizures) or severe CNS depression * Protracted vomiting **Treatment:** * **Naloxone** may reverse the CNS and respiratory depressant effects of the drug, but it **cannot** be expected to halt the vomiting. * **Atropine** has been suggested to treat severe bradycardias associated with overdose. * If protracted vomiting occurs from conjunctival administration, thoroughly flush the eye with sterile saline.
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。