A nurse is caring for a patient who has been newly prescribed ondansetron (Zofran) for post-operative nausea. What is the mechanism of action for ondansetron?
Ondansetron agonizes serotonin receptors on afferent vagal neurons.
Ondansetron agonizes serotonin receptors in the medulla oblongata.
Ondansetron agonizes dopaminergic receptors in the vestibular apparatus.
Ondansetron blocks serotonin receptors in the chemoreceptor trigger zone.
The Correct Answer is D
A. Ondansetron agonizes serotonin receptors on afferent vagal neurons. – This is incorrect. Ondansetron works by blocking, not activating, serotonin (5-HT3) receptors in areas involved in nausea and vomiting.
B. Ondansetron agonizes serotonin receptors in the medulla oblongata. – This is incorrect. Ondansetron does not act as an agonist at serotonin receptors in the medulla oblongata; instead, it antagonizes receptors to reduce nausea.
C. Ondansetron agonizes dopaminergic receptors in the vestibular apparatus. – This is incorrect. Ondansetron does not affect dopaminergic receptors or the vestibular apparatus. Medications like promethazine address dopaminergic pathways.
D. Ondansetron blocks serotonin receptors in the chemoreceptor trigger zone. – This is correct. Ondansetron acts as a 5-HT3 receptor antagonist, blocking serotonin receptors in the chemoreceptor trigger zone and vagal nerve terminals, effectively preventing nausea and vomiting.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is {"dropdown-group-1":"A","dropdown-group-2":"C"}
Explanation
- Docusate sodium: This is a surfactant laxative that helps soften stools by allowing water and fats to penetrate the stool, making it easier to pass.
- Loperamide: This medication is an anti-diarrheal agent that works by slowing down gut movement, which helps reduce the frequency of diarrhea.
Correct Answer is D
Explanation
A. Sucralfate does not neutralize gastric acid; antacids are responsible for neutralization.
B. Sucralfate does not mimic endogenous prostaglandins. Medications like misoprostol act as prostaglandins to protect the stomach lining.
C. Sucralfate does not block H2 receptors. Medications like cimetidine or ranitidine work through this mechanism to reduce acid production.
D. Sucralfate creates a viscous, protective barrier that adheres to the ulcer site, shielding it from further damage by gastric acid, bile, and pepsin for up to 6 hours, thereby promoting healing.
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