Question

All the following are true with Metoclopramide except:

• A. 5HT1 receptor antagonist
• B. D2 receptor antagonist
• C. 5HT3 receptor antagonist
• D. 5HT4 receptor agonist

Answer 1

The Correct Option is A

Metoclopramide is a medication that is primarily used to treat nausea and vomiting, as well as to facilitate gastric emptying in cases of gastroparesis. To correctly identify the exception regarding its mechanism of action, we must evaluate each of the given receptor interactions.

1. D2 Receptor Antagonist: Metoclopramide acts as a dopamine D2 receptor antagonist. This action is responsible for its antiemetic effects, as blocking D2 receptors in the chemoreceptor trigger zone of the brain helps control nausea and vomiting.
2. 5HT3 Receptor Antagonist: Metoclopramide also has activity as a 5HT3 receptor antagonist. This contributes further to its ability to prevent nausea and vomiting.
3. 5HT4 Receptor Agonist: Metoclopramide acts as a 5HT4 receptor agonist, which enhances gastrointestinal motility. This action helps in promoting digestion and controlling gastrointestinal symptoms such as gastroparesis.
4. 5HT1 Receptor Antagonist: This option is incorrect regarding Metoclopramide. Metoclopramide does not act as a 5HT1 receptor antagonist. Its mechanisms of action are more related to D2 receptor antagonism, 5HT3 receptor antagonism, and 5HT4 receptor agonism, which explains its therapeutic effects.

Hence, the correct answer is 5HT1 receptor antagonist, as it does not accurately describe the action profile of Metoclopramide.