Prochlorperazine

Prochlorperazine is a phenothiazine with centrally acting antiemetic properties. It has been used in dogs and cats to control selected causes of vomiting, either alone or in historical combination products. Its veterinary use is largely empirical, and the antiemetic role is distinct from the sedative effects that can accompany phenothiazine activity.

Group

Phenothiazine antiemetic

Mechanism of Action

Prochlorperazine antagonizes dopamine D2 receptors in the chemoreceptor trigger zone and related central pathways involved in emesis. This reduces transmission of dopamine-mediated vomiting signals to the brainstem vomiting network. Additional interactions with adrenergic, histaminergic and muscarinic receptors contribute to its wider pharmacologic profile and central depressant effects.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Vomiting	0.1–0.5 mg/kg	IM, IV, SC	Every 6–8 h
Vomiting	0.5–1 mg/kg	PO	Every 6–8 h
Vomiting	0.5 mg/kg	IM, SC	Every 8 h	Ensure adequate hydration.
Vomiting	0.1 mg/kg	IM	Every 6–8 h	Extreme caution with dehydration or hypotension.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Vomiting	0.1–0.5 mg/kg	IM, IV, SC	Every 6–8 h
Vomiting	0.5–1 mg/kg	PO	Every 6–8 h
Vomiting	0.5 mg/kg	IM, SC	Every 8 h	Ensure adequate hydration.

Indications

Empirical treatment of selected centrally mediated or drug-associated vomiting in dogs and cats.
Historical adjunctive treatment of vomiting associated with selected gastrointestinal disorders, with limited controlled clinical efficacy evidence.

Contraindications

Seizure-prone or other CNS disease requires caution.

Interactions

Potentiates sedatives.

Adverse effects

Sedation, hypotension and extrapyramidal movement disorders.

Toxicity

Severe phenothiazine effects include hypotension, CNS depression and extrapyramidal abnormalities. Manage circulation and neurologic signs with a patient-specific plan.

Preparations

Preparation	Form	Strength	Route
Prochlorperazine maleate 5 mg	Tablet	5 mg / tablet	PO
Prochlorperazine maleate 10 mg	Tablet	10 mg / tablet	PO
Prochlorperazine maleate 25 mg	Tablet	25 mg / tablet	PO
Prochlorperazine edisylate injection 5 mg/mL	Injection	5 mg / mL	IM, IV, SC

Monitoring and Administration

Observe sedation, blood pressure and abnormal movements. Discard injectable solution with milky precipitate; protect from light.

Do not use prochlorperazine solution with visible precipitate or substantial discoloration; slight yellowing alone does not establish potency loss.