Metoclopramide: a Dopamine Receptor Antagonist

A dopamine receptor antagonist, metoclopramide has unique properties of increasing lower esophageal sphincter pressure and increasing the rate of gastric emptying. These gastrointestinal motility actions are useful in the treatment of diabetic gastroparesis and severe gastroesophageal reflux and in postoperative situations involving visceral atony. Metoclopramide is a useful adjunctive drug for intestinal intubation and radiologic examination. It has also been used intravenously to control the nausea and vomiting of intensive cancer chemotherapy, such as with cisplatin. Metoclopramide is a powerful antiemetic because of its combined actions on the chemoreceptor trigger zone and intestinal motility. This agent is generally not intended for long-term use. The oral preparations are recommended for four to 12 weeks of therapy. Use of parenteral metoclopramide should be limited to one or two days. The most common adverse reactions are restlessness, drowsiness, fatigue and lassitude. Extrapyramidal symptoms occur rarely and only with high dosage or prolonged use.