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 B
Explanation
A. 4 teaspoons – This is incorrect because 4 teaspoons would provide 400 mg (100 mg x 4 = 400 mg), but the correct dose per administration is 400 mg. However, this is not the correct calculation, as only 2 teaspoons are needed.
B. 2 teaspoons – This is correct. The prescribed dose is 400 mg, and since the medication concentration is 100 mg per teaspoon, 2 teaspoons (100 mg x 2 = 200 mg) is the correct dose for each administration.
C. 1 teaspoon – This is incorrect because 1 teaspoon would only provide 100 mg, and the prescribed dose is 400 mg. This is not enough to meet the prescribed dose.
D. 3 teaspoons – This is incorrect because 3 teaspoons would provide 300 mg (100 mg x 3 = 300 mg), which is not enough to meet the prescribed 400 mg dose.
Correct Answer is ["A","B","C","D"]
Explanation
A. "Complications of this medication include tardive dyskinesia and prolonged QT interval." This is correct. Metoclopramide (Reglan) can cause side effects such as tardive dyskinesia, a movement disorder, and may prolong the QT interval, which can increase the risk of arrhythmias.
B. "The IV form of this medication is used for control of postoperative and chemotherapy-induced nausea and vomiting, as well as facilitation of small bowel intubation and examination of the GI tract." This is correct. The IV form of metoclopramide is commonly used for these indications, particularly for nausea and vomiting related to chemotherapy or surgery, as well as aiding in small bowel intubation.
C. "Complications of this medication include tardive dyskinesia and sedation." This is correct. In addition to tardive dyskinesia, metoclopramide can also cause sedation, making patients feel drowsy or lethargic.
D. "The oral form is used for diabetic gastroparesis (delayed stomach emptying with gas and bloating) and management of GERD through its ability to increase gastric motility." This is correct. The oral form of metoclopramide is frequently used to treat diabetic gastroparesis by improving gastric emptying, as well as managing gastroesophageal reflux disease (GERD) by enhancing motility.
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