Which is a dopamine receptor antagonist and is approved by the FDA to treat nausea and vomiting in patients with gastroesophageal reflux disease?

1. A

   Ivermectin

2. B

   Metoclopramide

3. C

   Azathioprine

4. D

   Acamprosate

Appeared in: PGICH Noida NO-2025

Explanation

• Metoclopramide is a dopamine D2 receptor antagonist, which provides its antiemetic (anti-nausea/vomiting) effect by acting on the chemoreceptor trigger zone (CTZ) in the brain.
• It also functions as a prokinetic agent, increasing gastrointestinal motility, accelerating gastric emptying, and increasing lower esophageal sphincter (LES) tone.
• This dual mechanism of action makes it an effective and FDA-approved treatment for nausea and vomiting associated with gastroesophageal reflux disease (GERD) and diabetic gastroparesis.

Why Other Options Were Wrong

• Option A: Ivermectin is an antiparasitic medication and has no dopamine-blocking or prokinetic properties relevant to treating GERD or nausea.
• Option C: Azathioprine is an immunosuppressant drug used to dampen the immune system; it does not target dopamine receptors or treat GI motility disorders like GERD.
• Option D: Acamprosate acts on brain neurotransmitter systems (GABA and glutamate) to help maintain abstinence in alcohol dependence; it is not an antiemetic or prokinetic agent.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Pharmacology of prokinetic and antiemetic drugs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Nurses must diligently monitor patients on metoclopramide for extrapyramidal symptoms (EPS), especially tardive dyskinesia (TD), a serious, often irreversible movement disorder. The FDA has issued a black box warning for TD with use longer than 12 weeks.
• Patient education is a key nursing responsibility. Advise patients to immediately report any involuntary movements of the face, tongue, or limbs. Also, caution them about potential drowsiness and to avoid driving until the effects are known.
• What if? If a patient develops uncontrollable muscle spasms of the face or neck (an acute dystonic reaction) after a dose of metoclopramide, the nurse's priority is to ensure a patent airway and immediately notify the provider. An anticholinergic agent like diphenhydramine is often administered as an antidote.

How to Approach the Question

• First, dissect the question to identify the essential criteria for the correct drug: 1) it must be a 'dopamine receptor antagonist', and 2) it must be approved for 'nausea and vomiting' in 'gastroesophageal reflux disease (GERD)'.
• Next, review the four options and recall their primary drug class and main clinical use.
• Systematically evaluate each option. Ivermectin is an antiparasitic. Azathioprine is an immunosuppressant. Acamprosate is for alcohol dependence. None of these match the criteria.
• Focus on Metoclopramide. Recall that it is a well-known GI medication. Its mechanism involves dopamine antagonism, and it is frequently used for motility issues like gastroparesis and GERD.
• Confirm the choice by connecting all the dots. Metoclopramide's action as a dopamine antagonist (antiemetic) and a prokinetic agent (for GERD) makes it the only option that fits all parts of the question.

Concept Tested & Keywords

• Concept Tested: Pharmacology of prokinetic and antiemetic drugs
• Stem keywords: dopamine receptor antagonist, FDA approved, nausea and vomiting, gastroesophageal reflux disease
• Lead-in keywords: Which is
• Negative lead-in flag: false

Question ID

QgbRWDkRlnKhoxoIJPwJ1h

Copy ID

Reference Book

E6 Pharmacology Nursing Lilley 11e Part 3 p. 188-190

E6 Pharmacology Nurses Shanbhag 3e p. 211-213