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.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
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.
Correct Answer is B
Explanation
A. Metformin does not typically cause hypoglycemia because it works by decreasing hepatic glucose production and improving insulin sensitivity, not directly lowering blood sugar levels.
B. Somnolence could indicate lactic acidosis, a rare but serious adverse effect of metformin that warrants immediate medical attention.
C. Fluid retention is not a known adverse effect of metformin. Other medications, such as certain thiazolidinediones, are associated with this complication.
D. Hyperglycemia is not a typical adverse effect of metformin; instead, it helps manage blood glucose levels in clients with type 2 diabetes mellitus.
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