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Metoclopramide is used in veterinary medicine to stimulate the motility of the upper GI tract. It has minimal effect on the lower GI tract and colon. Metoclopramide increases peristalsis of the small intestine and increases tone and strength of contractions in the stomach while causing relaxation of the pyloric sphincter. Consequently, metoclopramide speeds gastric emptying and, possibly, intestinal transit times. It does not stimulate gastric, pancreatic or biliary secretions.
Metoclopramide acts as a central antiemetic by blocking the uptake of dopamine at the chemo-receptor trigger zone in dogs. Additionally, part of its actions on the upper GI tract include increasing the sphincter pressure in the lower esophagus and reducing gastroesophageal reflux, which may also be helpful for decreasing vomiting.
Metoclopramide is well-absorbed orally. It penetrates
the central nervous system (CNS) well, which may be relevant because of
CNS side effects. Metoclopramide crosses the placenta and is concentrated
in milk at twice the level found in plasma. It is primarily excreted in
the urine.
Metoclopramide is used in a wide variety of gastric-motility disorders, including ileus, and gastritis. Because so many upper GI-emptying disorders present with nausea and vomiting due to abnormal gastric emptying, metoclopramide is particularly useful because of its effects on motility and its function as a central antiemetic. It may also be used to control nausea and vomiting in cases of renal failure, acute hepatic failure and hepatitis, and in animals undergoing chemotherapy.
Intravenous metoclopramide is used in foals to treat
illeus associated with neonatal hypoxia. In these foals, metoclopramide
should improve gastric emptying and upper-GI function. Metoclopramide
is occasionally used in cases of post-operative illeus in the adult horse;
however, neurologic side effects limit its usefulness in adult horses.
• In dogs, rare CNS side effects may include either
sedation or hyperactivity; cats may experience hyperactivity or disorientation.
Signs of neurotoxicity may occur in both dogs and cats at therapeutic
levels. These signs will usually resolve within a few days of discontinuing
the metoclopramide. Diphenhydramine may help reduce movement disorders,
such as twisting movements of the face, neck, trunk or limbs, as well
as CNS depression, nervousness, restlessness or frenzied behavior (especially
in cats). Constipation may occur in both species.
• In adult horses, CNS side effects (alternating both sedation and
excitement) and colic may occur with IV administration. Side effects are
less common in foals.
• Metoclopramide should not be used in animals
with GI obstruction, perforation or hemorrhage.
• Metoclopramide should not be used in animals with a history of
seizures, as it may lower the seizure threshold.
• Metoclopramide should not be used in animals with pheochromocytoma.
• Metoclopramide may affect the absorption of other
oral medications including cyclosporine and tetracyclines.
• Cholinergic drugs such as bethanechol may increase the effect of
metoclopramide on the GI system.
• Metoclopramide may increase the CNS depressant effects of phenothiazine
tranquilizers, sedatives, narcotics, barbiturates, antihistamines and
anesthetic agents.
• Extrapyramidal effects of metoclopramide may also be increased
with concurrent use of phenothiazine tranquilizers, narcotics and butyrophenones.
• Acute hypotension may occur with IV use of metoclopramide and anesthetic
drugs. Hypertension may occur with concurrent use of metoclopramide and
MAO inhibitors.
• Opiate analgesics, atropine and other anticholinergic drugs may
antagonize any effects on GI motility.
• Metoclopramide has a high LD50 and, as a consequence,
it is unlikely that an oral overdose will cause death.
• Overdose will cause similar but more severe clinical signs discussed
under side effects.
• If the overdose was recent, the stomach should be emptied using
standard protocols.
• Anticholinergics, such as diphenhydramine, may be used to decrease
CNS signs.
Dr.
Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania.
She has a master's degree in animal science from the University of Delaware
and graduated from the University of Pennsylvania School of Veterinary Medicine
in 1982.
She began to develop her interest in client education and medical writing 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.
Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.
You can purchase books by Dr. Forney at www.exclusivelyequine.com
The information contained on this site
is general in nature and is intended for use as an informational aid. It does
not cover all possible uses, actions, precautions, side effects, or interactions
of the products shown, nor is the information intended as medical advice or
diagnosis for individual health problems or for making an evaluation as to the
risks and benefits of using a particular product. You should consult your doctor
about diagnosis and treatment of any health problems. Information and statements
have not been evaluated by the Food and Drug Administration ("FDA"),
nor has the FDA approved the products to diagnose, cure or prevent disease.
Wedgewood compounded veterinary medicines are not intended for use in food and food-producing animals.
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