Vetdrugs 2.0Apomorphine is a centrally acting emetic used chiefly in dogs after selected recent ingestions when removal of stomach contents is expected to help. Although chemically derived from an opioid, its emetic action is dopaminergic rather than conventional opioid analgesia. Selection of the patient and ingested material determines whether vomiting is appropriate.
It is not a general antidote and cannot reverse toxin already absorbed. Feline response is less reliable and adverse excitation is a concern; historical feline use does not support routine administration to cats.
Group
Dopaminergic emetic
Mechanism of Action
Apomorphine crosses into central emetic pathways and stimulates dopamine D2 receptors in the chemoreceptor trigger zone, which communicates with the medullary vomiting circuitry. Activation coordinates the autonomic and muscular responses that expel gastric contents.
The canine chemoreceptor trigger zone responds well to this dopaminergic stimulus, which explains the rapid and relatively reliable emetic effect in dogs. Species differences in emetic receptor pathways explain why an effective canine emetic is not automatically a useful feline emetic.
Parenteral and mucosal administration can provide effective exposure, whereas extensive first-pass metabolism limits ordinary swallowed oral administration. Central drug effects can also include sedation or other neurologic changes, so persistence of depression after vomiting is not evidence that further emesis is required.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Induction of emesis | 0.03–0.05 mg/kg | IM | Once | One administration only; less effective in cats. |
| Induction of emesis | 0.1 mg/kg | SC | Once | One administration only; less effective in cats. |
| Induction of emesis - conjunctival administration | Reference only | TOPICAL | Once | Conjunctival sac only. Dissolve a 6 mg tablet in 1–2 mL saline and rinse away after emesis; ocular route is not represented in the calculator. |
| Induction of emesis | 0.03 mg/kg | IV | Once | One administration; use an IV-compatible sterile formulation. |
| Induction of emesis - IV alternative | 0.04 mg/kg | IV | Once | One administration; use an IV-compatible sterile formulation. |
| Induction of emesis - IM alternative | 0.08 mg/kg | IM | Once | |
| Induction of emesis - SC alternative | 0.08 mg/kg | SC | Once |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Induction of emesis | 0.03–0.05 mg/kg | IM | Once | Historical feline alternative; apomorphine is not recommended for induction of emesis in cats. One administration only; less effective in cats. |
| Induction of emesis | 0.1 mg/kg | SC | Once | Historical feline alternative; apomorphine is not recommended for induction of emesis in cats. One administration only; less effective in cats. |
| Induction of emesis - conjunctival administration | Reference only | TOPICAL | Once | Historical feline alternative; apomorphine is not recommended for induction of emesis in cats. Conjunctival sac only. Dissolve a 6 mg tablet in 1–2 mL saline and rinse away after emesis; ocular route is not represented in the calculator. |
| Induction of emesis - historical IV alternative | 0.04 mg/kg | IV | Once | Historical feline alternative; apomorphine is not recommended for induction of emesis in cats. Feline use is controversial, less reliable and potentially less safe; a feline-appropriate emetic is generally preferred. |
| Induction of emesis - historical alternative | 0.08 mg/kg | IM, SC | Once | Historical feline alternative; apomorphine is not recommended for induction of emesis in cats. Feline use is controversial; a feline-appropriate emetic is generally preferred. |
Indications
- Induction of emesis in appropriately selected dogs after recent ingestion of a potentially toxic substance, when gastric decontamination is expected to be beneficial.
Contraindications
- Do not induce emesis with absent protective airway reflexes, severe CNS depression, seizures, hypoxia, dyspnea, shock or extreme weakness.
- Avoid after caustic ingestion, repeated prior vomiting or ingestion of CNS depressants; petroleum distillates create major aspiration risk.
- Do not use to induce vomiting in rabbits or rodents.
- Morphine hypersensitivity. Feline use is less effective and controversial.
- Do not use apomorphine as a routine feline emetic; select a feline-appropriate alternative.
Interactions
- Acepromazine, atropine and other antiemetics can diminish emesis.
- Other CNS/respiratory depressants can add to depression.
- Avoid concomitant ondansetron because severe hypotension has been reported in people.
Adverse effects
- Sedation may mask poisoning signs.
- Ocular irritation from acidic solution.
- High doses can cause excitement.
Toxicity
Overdose may cause prolonged vomiting, excitation, seizures, CNS depression or cardiorespiratory depression. Naloxone may reverse CNS and respiratory effects but does not reliably stop vomiting. Rinse conjunctival drug away when applicable.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Apomorphine hydrochloride 10 mg/mL injection The emesis regimens here do not support IV administration. | Injection | 10 mg / mL | IM, SC |
Monitoring and Administration
Limit to one administration. Vomiting generally occurs within 3–10 minutes in dogs; continue monitoring the original toxicant because emesis removes less than half the ingested quantity.
For conjunctival administration, dissolve a 6 mg tablet in 1–2 mL 0.9% saline, place in the conjunctival sac, then rinse residual drug away after vomiting. This is ocular mucosal administration, not oral dosing of the tablet.
Protect solutions from air and light; green discoloration indicates decomposition. A particular 3 mg/mL compounded solution had 6-month room-temperature stability.
Canine IV emesis protocols are supported; use only a sterile formulation suitable for that route, not a tablet dispersion or an SC-only human device. Monitor respiratory, cardiovascular and CNS status. Vomiting does not remove all toxicant and does not end poisoning treatment.
An ocular alternative is 0.25 mg/kg in the conjunctival sac, with prompt rinsing after sufficient emesis; do not confuse ocular administration with oral swallowing. Do not use discolored or precipitated solutions. Tablet-derived sterile filtrates have a separate 2-day refrigerated, light-protected period; their preparation requires aseptic pharmacy procedures.