What is the function of metoclopramide as an antiemetic?

• A. To increase gastric motility and reduce nausea
• B. To block dopamine receptors exclusively in the brain
• C. To serve as a histamine antagonist
• D. To induce sedation without antiemetic effect

Answer: (A)

Metoclopramide functions primarily as an antiemetic by increasing gastric motility and reducing nausea. It acts as a prokinetic agent, which means it enhances the movement of the stomach and intestines, facilitating the passage of food and reducing feelings of fullness or nausea that can lead to vomiting. This action is particularly beneficial for patients experiencing delays in gastric emptying, such as those with gastroparesis. Additionally, metoclopramide has central effects where it blocks dopamine receptors in the chemoreceptor trigger zone (CTZ), which also contributes to its antiemetic effect. However, the key aspect of metoclopramide’s function as an antiemetic lies in its ability to increase gastric motility, thus addressing both nausea and the underlying gastrointestinal stasis that may contribute to emesis.