Emesis With Consecutive Administration of Ropinirole & Apomorphine

In the Literature

Saloranta LI, Levijoki JM, Vuorela AM. An experimental study of consecutive administration of ropinirole and apomorphine for emesis induction in dogs. J Vet Emerg Crit Care (San Antonio). 2024;34(1):31-39. doi:10.1111/vec.13339

The Research …

Early emesis induction is crucial for decontamination in cases of toxin ingestion.¹ Apomorphine injections and ropinirole eye drops are common emetic agents for dogs and have similar efficacy for inducing emesis and evacuating gastric contents.² Ropinirole, a selective dopamine D₂-like receptor agonist, triggers vomiting via activation of the chemoreceptor trigger zone.² Apomorphine, a nonselective dopamine agonist, also stimulates adrenoreceptors and mu-opioid receptors.² The safety and effectiveness of consecutive ropinirole and apomorphine administration are unknown.

This prospective crossover study^a evaluated 4 combinations of apomorphine and ropinirole in 6 beagles. Two combinations simulated partially successful administration of either apomorphine or ropinirole via IV infusion, followed by a clinical dose of the remaining drug, and 2 combinations comprised consecutive administration of the maximum labeled dose of one drug, followed by the maximum labeled dose of the second drug.

Results showed that combining both agents was safe and effective for inducing emesis. The total number of vomiting episodes did not significantly differ (average between 4.3 and 8.8 in each treatment group). Dogs in all groups exhibited signs of nausea, vomiting, and lethargy, without significant differences among groups. Local ocular signs (ie, conjunctival hyperemia, blepharospasm) were observed in all groups, even when ropinirole was administered parenterally. Moderate to marked tachycardia and mild muscle tremors also occurred in all groups. Pharmacokinetic analysis showed prior treatment with apomorphine significantly reduced absorption of ropinirole eye drops, possibly due to the alpha-adrenergic agonist effects of apomorphine on the conjunctival epithelium.

… The Takeaways

Key pearls to put into practice:

• Emesis should be avoided in patients with clinical signs of toxicosis, decreased mentation (because of decreased ability to protect the airway), or signs of cardiovascular shock or respiratory distress. Emesis is also contraindicated in patients that ingested corrosive agents, volatile substances, and/or sharp foreign body objects. Ropinirole should be avoided in dogs with ocular disease.

• Consecutive administration of ropinirole and apomorphine was safe and effective in this study. Administering both of these medications should be strongly considered in patients at risk for severe toxicosis, especially when no antidote is available and the outcome relies on effective and early decontamination. Consecutive administration may also be considered when an initial dose is only partially successful.

• Adverse effects of consecutive administration of ropinirole and apomorphine may include excessive vomiting, mild ocular signs, and/or transient tachycardia. Consecutive administration should be avoided in patients with underlying heart disease. Dehydration may be exacerbated in patients with protracted vomiting, and hydration status should be closely monitored.

• Metoclopramide (0.5 mg/kg SC or IV) can be given for protracted vomiting and other dopaminergic signs (eg, lethargy, ocular irritation, tremors). Maropitant (1 mg/kg IV, not SC) is also an effective antiemetic but does not reduce dopaminergic signs.³ Activated charcoal administration may prompt use of an antiemetic, as signs of nausea in the current study continued for 45 to 90 minutes following emetic administration.

^a The study was sponsored by Orion Corporation, Orion Pharma.