Metoclopramide

Metoclopramide In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Has an antiemetic effect via central dopamine (D2) receptor antagonism, and at higher doses of 5HT3 antagonism, at the chemoreceptor trigger zone.
• Dopamine receptors are more important in the vomiting reflex in dogs than in cats, and so metoclopramide is less likely to be effective in cats.
• A gastric prokinetic effect is a result of local D2 antagonism and stimulation of muscarinic acetylcholine and 5HT4 receptors leading to increases in oesophageal sphincter pressure, the tone and amplitude of gastric contractions and peristaltic activity in the duodenum and jejunum, and relaxation of the pyloric sphincter.
• Prokinetic effects appear to be weak and distal intestinal motility is not significantly affected.

Uses of Metoclopramide

• Treatment of vomiting of many causes.
• The prokinetic effect may be beneficial in reflux oesophagitis.

Dose of Metoclopramide in Dogs and Cats

Dogs, Cats:

• All uses: 0.25–0.5 mg/kg i.v., i.m., s.c., p.o. q12h or 0.17–0.33 mg/kg i.v., i.m., s.c., p.o. q8h or 1–2 mg/kg i.v. over 24 hours as a constant rate infusion.

Side Effects of Metoclopramide in Dogs and Cats

• Unusual, although more common in cats than dogs, and probably relate to relative overdosing and individual variations in bioavailability.
• The observed effects are transient and disappear when treatment is stopped.
• They include changes in mentation and behaviour (agitation, ataxia, abnormal positions and/ or movements, prostration, tremors, aggression and vocalization).
• It may also cause sedation.
• Cats may exhibit signs of frenzied behaviour or disorientation.
• Very rarely allergic reactions may occur

Contraindications of Metoclopramide in Dogs and Cats

• Do not use where GI obstruction or perforation is present or for >48 hours without a definitive diagnosis.
• Do not use it in the case of gastrointestinal haemorrhage.
• Do not use it in epileptic patients.
• Reduce dose by 50% in animals with reduced kidney or liver function.
• Avoid in dogs with pseudopregnancy.
• In animals with phaeochromocytoma, metoclopramide may induce a hypertensive crisis.

Some Notes:

• The activity of metoclopramide may be inhibited by antimuscarinic drugs (e.g. atropine) and narcotic analgesics.
• The effects of metoclopramide may decrease (e.g. cimetidine, digoxin) or increase (e.g. oxytetracycline) drug absorption.
• The absorption of nutrients may be accelerated, thereby altering insulin requirements and/or timing of its effects in diabetics.
• Phenothiazines may potentiate the extrapyramidal effects of metoclopramide.
• The CNS effects of metoclopramide may be enhanced by narcotic analgesics or sedatives.