Apomorphine

Apomorphine for Dogs: Dosage, Uses, and Side Effects Guide

Overview

Apomorphine is mainly For dogs to induce vomiting and works quickly by stimulating dopamine receptors in the brain. In most cases, it causes vomiting within a few minutes, especially when given by injection. For Cats, it’s not used as it’s usually not effective for them and we can use dexmedetomidine instead.

There are some important cases where apomorphine shouldn’t be used — such as in animals that can’t vomit (like rabbits and rodents) or if vomiting could cause harm, for example, after swallowing corrosive substances or in animals with seizures or at risk of aspiration. Because of potential health risks to people handling it, apomorphine is considered hazardous and should be handled carefully, following proper safety steps.

Uses of Apomorphine

Main Apomorphine Uses in Animals:

• Dogs: Apomorphine for dogs is a potent emetic used after ingestion of toxins or foreign bodies. It is effective in about 90%–100% of cases and is most beneficial when given within 2 hours of ingestion. Prompt use can help prevent absorption of harmful substances.
• Cats: Apomorphine is generally avoided in cats due to poor effectiveness and potential safety concerns. Alpha-2 agonists like dexmedetomidine are preferred for inducing emesis in feline patients.
• Contraindicated species: Apomorphine should not be used in species unable to vomit (e.g., rabbits, rodents) or in cases where vomiting could cause harm (e.g., seizures, coma, corrosive ingestion).

Dosage of Apomorphine

Dosage in Dogs (Extra-label Use)

Apomorphine injection For Dogs Is Given:

• Intravenous (IV): 0.01 – 0.04 mg/kg – induces vomiting rapidly, often within 1–5 minutes.
• Subcutaneous (SC): 0.01 – 0.04 mg/kg – effective emesis occurs within 13.5 minutes on average (range: 3–32 minutes).
• Intramuscular (IM): 0.01 – 0.04 mg/kg – slowest onset compared to IV and SC routes.

Apomorphine Oral (PO): 0.25 mg/kg – approximately one 6.5 mg tablet per 26 kg body weight. Efficacy may vary.

Dosage in Ferrets (Extra-label Use)

• IV, IM, or SC: 0.04 mg/kg
• Subconjunctival: 0.25 mg/kg

Side Effects of Apomorphine in Dogs

Common Apomorphine Side Effects:

1. Vomiting: Rapid and sometimes prolonged vomiting is the most common effect. Prolonged nausea may follow, especially with high doses or sensitive dogs.
2. Sedation: Some dogs may become lethargic or sleepy after administration. Sedation is more common when apomorphine is applied in the eye (subconjunctival route).
3. Tachycardia: Fast heart rate (reported in about 16% of cases) may occur, especially with eye application.
4. Eye Irritation: When given via the eye, redness, discomfort, or irritation can happen. Rarely, corneal ulcers have been reported.
5. CNS Effects: Dogs with MDR1 gene mutation may experience stronger effects such as heavy sedation or uncoordinated movement. Use with caution in sensitive breeds (e.g., Collies).
6. Overdose Signs: High doses may cause severe vomiting, drooling, low blood pressure, slow heart rate, and breathing difficulty. In rare cases, seizures or collapse may occur.

Contraindications of Apomorphine

Important Apomorphine Contraindications To Consider:

1. Related To Species: Do not use in animals that cannot vomit, such as rabbits, rodents, and horses.
2. Clinical Conditions: Avoid use in patients with:
   • Seizures or risk of seizures (e.g., from strychnine poisoning).
   • Severe CNS depression or coma.
   • Respiratory distress or cardiovascular shock.
   • Weak swallowing or pharyngeal reflex (risk of aspiration).
   • History of aspiration pneumonia.
   • Ingestion of sharp objects or corrosive substances (e.g., acids, alkalis, petroleum products).
3. Drug Sensitivity: Contraindicated in animals sensitive to opioids or with known hypersensitivity to apomorphine or morphine.
4. Toxin Ingestion: Do not use if the ingested toxin causes CNS depression (e.g., barbiturates) or if the animal has already vomited multiple times.
5. Liver Impairment: Use with caution in animals with liver disease, as drug effects may last longer.

Important Notes

1. Effectiveness Timing: Apomorphine works best when given soon after toxin ingestion – ideally within 1 to 2 hours. The sooner it’s administered, the more effective it is at removing harmful substances.
2. Species-Specific Use: Apomorphine is primarily used in dogs. It is generally not effective or safe in cats. For cats, other drugs (like dexmedetomidine) are preferred to induce vomiting.
3. Administration Methods: The drug can be given by injection (IV, SC, IM) or via the eye (subconjunctival route). The IV route causes the fastest vomiting; SC is next quickest. Oral forms are less reliable.
4. Drug Stability: Store apomorphine tablets in a tightly sealed container at room temperature, away from light and moisture. Discard any discolored (greenish or bluish) tablets or solutions.
5. Handling Safety: Apomorphine is classified as a hazardous drug by NIOSH. Always wear gloves and use protective gear when handling or preparing this medication to avoid accidental exposure.