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 C
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","C"]
Explanation
A. "I should apply this patch behind my ear.": This is correct because the scopolamine patch is designed to be applied behind the ear, where it can effectively deliver medication through the skin.
B. "This patch should be replaced every 7 days.": This is incorrect because the scopolamine patch should be replaced every 72 hours (3 days), not every 7 days.
C. "I should not use a second patch if the initial patch is ineffective.": This is correct because using more than one patch at a time can lead to an overdose of the medication, which can cause serious side effects.
D. "Before putting on my patch, I should wipe the area with an alcohol swab.": This is incorrect because using an alcohol swab can irritate the skin and affect the absorption of the medication. The area should be clean and dry, but not cleaned with alcohol.
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