Gastrointestinal prokinetic therapy: Dopaminergic antagonist drugs

Motility disorders of the esophagus, stomach, small intestine, and colon are common in dogs and cats. These disorders have usually been treated primarily by dietary management and surgical intervention; however, gastrointestinal prokinetic therapy is assuming increasing clinical importance. In parts I through IV of this five-part Continuing Education Series, gastrointestinal prokinetic agents are grouped into four categories. For each category of agents, the mechanisms of action, site of activity, and indications for use will be discussed. Part I contains information about the dopaminergic antagonist drugs, which inhibit peripheral and/or central dopamine receptors. Metoclopramide and domperidone, for example, reverse the gastric relaxation induced by dopamine infusion in dogs. The agents abolish the vomiting that is associated with apomorphine administration. Part II of the series will deal with motilin-like drugs, Part III will consider serotonergic drugs, and part IV will discuss the acetylcholinesterase inhibitors or parasympathetic potentiating drugs. The final part will deal with the diagnosis and management of esophageal, gastric, and colonic motility disorders; clinical preferences for gastrointestinal prokinetic agents will be highlighted.