Metoclopramide Hydrochloride — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	0.2-0.5 mg/kg	q8h	Duration: As needed, typically 3-5 days Notes: Administer 30 minutes before meals. For GERD, use 0.2-0.4 mg/kg q8h.
Dog	IV/IM/SC	0.2-0.5 mg/kg	q8h	Duration: As needed Notes: IV administration should be slow (over 15-30 minutes) to avoid adverse effects.
Cat	PO	0.2-0.4 mg/kg	q8h	Duration: As needed, typically 3-5 days Notes: Administer 30 minutes before meals. For hepatic lipidosis, use 0.2 mg/kg q8h.
Cat	IV/IM/SC	0.2-0.4 mg/kg	q8h	Duration: As needed Notes: IV administration should be slow.
Horse	PO	0.25-0.5 mg/kg	q8-12h	Duration: As needed Notes: Use with caution in horses with colic; monitor for signs of discomfort.
Horse	IV	0.1-0.2 mg/kg	q8-12h	Duration: As needed Notes: Slow IV administration.
Cattle	IV/IM/SC	0.1-0.3 mg/kg	q12-24h	Duration: As needed Notes: Off-label use; monitor for extrapyramidal signs.
Small Ruminants	IV/IM/SC	0.1-0.3 mg/kg	q12-24h	Duration: As needed Notes: Off-label use; monitor for extrapyramidal signs.
Rabbit	PO/SC	0.2-0.5 mg/kg	q8-12h	Duration: As needed Notes: Use with supportive care for GI stasis.
Bird/Poultry	PO/IM	0.5-1 mg/kg	q8-12h	Duration: As needed Notes: Limited data; use with caution.
Exotic/Other	PO/SC	0.2-0.5 mg/kg	q8-12h	Duration: As needed Notes: Dose based on extrapolation; monitor closely.

Clinical Indications & Species Uses

General Indications

Antiemetic for various causes
Prokinetic for gastrointestinal motility disorders

Dog (Canine)

Gastroesophageal reflux disease (GERD)
Gastritis and delayed gastric emptying
Vomiting associated with chemotherapy or other causes
Postoperative ileus
Gastric dilatation-volvulus (adjunctive therapy)
Esophageal reflux during anesthesia

Cat (Feline)

Gastroesophageal reflux disease (GERD)
Gastritis and delayed gastric emptying
Vomiting associated with chemotherapy or other causes
Postoperative ileus
Hepatic lipidosis (adjunctive therapy to stimulate appetite and gastric emptying)

Horse (Equine)

Gastroesophageal reflux disease (GERD)
Gastric ulceration (adjunctive therapy)
Postoperative ileus
Delayed gastric emptying

Cattle (Bovine)

Indigestion and ruminal atony (off-label use)
Traumatic reticuloperitonitis (adjunctive therapy)
Postoperative ileus

Small Ruminants (Sheep / Goat)

Indigestion and ruminal atony (off-label use)
Postoperative ileus

Rabbit & Small Mammals

Gastrointestinal stasis (ileus)
Gastric dilatation

Exotic & Other Species

Reptiles: gastrointestinal motility disorders (off-label)
Small mammals (e.g., ferrets): gastrointestinal stasis (off-label)

Pharmacology & Mechanism of Action

Drug Class: Prokinetic agent | Pharmacological Group: Benzamide derivative

Mechanism of Action: Metoclopramide is a dopamine (D2) receptor antagonist and a weak 5-HT3 receptor antagonist, with additional 5-HT4 receptor agonist activity. It enhances gastrointestinal motility by increasing the release of acetylcholine from postganglionic cholinergic neurons in the myenteric plexus, which stimulates muscarinic receptors in the smooth muscle of the upper GI tract. It also increases lower esophageal sphincter tone and relaxes the pyloric sphincter, promoting gastric emptying and intestinal transit. Its central antiemetic effect is primarily due to D2 receptor blockade in the chemoreceptor trigger zone (CTZ) of the brainstem.

Pharmacodynamics: Metoclopramide exerts prokinetic effects on the upper gastrointestinal tract, increasing the amplitude and frequency of gastric contractions, relaxing the pyloric sphincter, and enhancing peristalsis of the duodenum and jejunum. It does not stimulate gastric acid secretion. Its antiemetic action is central, raising the threshold for emetic stimuli. The drug also increases lower esophageal sphincter pressure, which is beneficial in gastroesophageal reflux disease. Onset of action is rapid after IV administration (1-3 minutes) and within 30-60 minutes after oral administration.

⚡ Pharmacokinetics Summary

Absorption: Rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1-2 hours. Bioavailability is approximately 80% in dogs and cats, but may be reduced by food. Absorption is rapid after IM and SC administration.

Distribution: Widely distributed into tissues, crosses the blood-brain barrier, and distributes into milk. Volume of distribution is approximately 3-5 L/kg in dogs. Protein binding is about 30%.

Metabolism: Metabolized primarily in the liver via conjugation (sulfate and glucuronide) and oxidation. The major metabolite is 4-amino-5-chloro-2-methoxybenzoic acid. In dogs, metabolism is extensive, with less than 10% excreted unchanged.

Excretion: Excreted primarily in urine (as metabolites) and to a lesser extent in feces. In dogs, approximately 60% of the dose is excreted in urine within 24 hours. Renal clearance is reduced in animals with renal impairment.

Half-Life: Dogs: approximately 1.5-2 hours; Cats: approximately 1.5-2 hours; Horses: approximately 2-3 hours; Cattle: approximately 2-4 hours.

Bioavailability: Oral: ~80% in dogs and cats; IM/SC: nearly 100%.

Protein Binding: Approximately 30% bound to plasma proteins.

Available Formulations & Strengths

Oral Tablet 5 mg, 10 mg (PO)

Oral Solution 1 mg/mL (PO)

Injectable Solution 5 mg/mL (IV/IM/SC)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to metoclopramide
Gastrointestinal obstruction, perforation, or hemorrhage
Pheochromocytoma (risk of hypertensive crisis)
Seizure disorders (may lower seizure threshold)
Extrapyramidal disorders (may exacerbate)
Use with caution in animals with renal impairment (dose adjustment may be needed)

Warnings & Clinical Precautions:

May cause extrapyramidal signs (e.g., tremors, ataxia, restlessness) especially in young animals and at high doses.
Use with caution in animals with hepatic impairment.
May cause sedation or agitation.
In horses, may cause colic-like signs; monitor closely.
In food animals, observe withdrawal times.
Do not use in animals with GI obstruction.
Use with caution in animals with congestive heart failure or hypertension (may cause fluid retention).

Adverse Effects & Reactions

Common:

Sedation
Restlessness
Diarrhea
Increased salivation
Vomiting (paradoxical)

Serious / Severe:

Extrapyramidal signs (tremors, ataxia, muscle spasms)
Seizures
Arrhythmias (rare)
Neuroleptic malignant syndrome (rare)

Rare:

Allergic reactions (rash, urticaria)
Blood dyscrasias (agranulocytosis, neutropenia)
Hepatotoxicity

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Anticholinergics (e.g., atropine)	May antagonize the prokinetic effects of metoclopramide.	Moderate
Opioid analgesics	May increase the risk of central nervous system depression and gastrointestinal effects.	Moderate
Phenothiazines (e.g., acepromazine)	Increased risk of extrapyramidal effects.	High
MAO inhibitors	Potential hypertensive crisis.	High
Digoxin	May reduce absorption of digoxin due to increased GI motility.	Moderate
Cimetidine	May reduce absorption of cimetidine.	Mild
Cyclosporine	May increase absorption of cyclosporine due to increased GI motility.	Moderate

Overdose & Toxicity Management

Signs of Toxicity:

Severe extrapyramidal signs (tremors, rigidity, opisthotonos)
Seizures
Hyperactivity
Disorientation
Respiratory depression
Cardiac arrhythmias

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Induce emesis (if recent and no contraindications) or perform gastric lavage. Administer activated charcoal to reduce absorption. For extrapyramidal signs, administer diphenhydramine (1-2 mg/kg IV or IM) or benzodiazepines (e.g., diazepam) to control seizures. Monitor vital signs and provide fluid therapy. In severe cases, consider anticholinergic agents (e.g., benztropine) but use with caution. There is no specific antidote.

Food Animal Withdrawal Times

🥩 Meat: 3 days🥛 Milk: 3 days

Withdrawal times are not officially established for metoclopramide in food animals. The values provided are conservative estimates based on pharmacokinetic data. Consult local regulations and a veterinary toxicologist for specific guidance.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature (20-25°C, excursions permitted to 15-30°C).

Light Sensitivity: Light-sensitive — protect from direct exposure.

Handling & Special Conditions: Protect from light. Keep container tightly closed. Do not freeze injectable solution.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs and cats (oral and injectable formulations). Not approved for food animals in the US.

Extra-Label (Off-Label) Use: In the US, extra-label use of metoclopramide in food animals is permitted under AMDUCA with a valid veterinary-client-patient relationship, provided that withdrawal times are extended and residues are not present. It is not approved for use in food animals in many countries; check local regulations.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Metoclopramide is a valuable prokinetic and antiemetic agent in veterinary medicine. It is particularly useful for managing gastroesophageal reflux, delayed gastric emptying, and chemotherapy-induced vomiting. In dogs and cats, it is often used as an adjunct in the treatment of gastric dilatation-volvulus and hepatic lipidosis. In horses, it can be used for postoperative ileus, but careful monitoring is required due to potential adverse effects. For rabbits and other small mammals, it is used off-label for gastrointestinal stasis. Dosing should be adjusted in patients with renal impairment. Adverse effects, especially extrapyramidal signs, are more common in young animals and at higher doses. Always consider the underlying cause of vomiting or motility disorders and use metoclopramide as part of a comprehensive treatment plan.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)