Metoclopramide is primarily used to treat nausea and vomiting, and to facilitate gastric emptying in patients with gastroparesis. It is potent dopamine receptor antagonist used for its antiemetic and prokinetic properties.

Metoclopramide is commonly used to treat nausea and vomiting (emesis) associated with conditions including: emetogenic drugs, uraemia, radiation sickness, malignancy, labor, and infection. It is also used by itself or in combination with paracetamol (acetaminophen) for the relief of migraine. It is considered ineffective in postoperative nausea and vomiting (PONV) at standard doses, and ineffective for motion sickness.

It appears to bind to dopamine D2 receptors where it is a receptor antagonist, and is also a mixed 5-HT3 receptor antagonist/5-HT4 receptor agonist. The anti-emetic action of metoclopramide is due to its antagonist activity at D2 receptors in the chemoreceptor trigger zone (CTZ) in the central nervous system (CNS)—this action prevents nausea and vomiting triggered by most stimuli. At higher doses, 5-HT3 antagonist activity may also contribute to the anti-emetic effect.

Formal Chemical Name (IUPAC)
4-amino-5-chloro-N-(2-(diethylamino)ethyl)-2-methoxybenzamide

References

http://en.wikipedia.org/wiki/Metoclopramide