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 B
Explanation
A. Hypothyroidism: This is incorrect. The client is taking levothyroxine (Synthroid) to treat hypothyroidism, and the symptoms described (diarrhea, weight loss, palpitations, heat intolerance) are more likely associated with excess thyroid hormone, not a lack of it.
B. Thyrotoxicosis: This is correct. The symptoms the client is experiencing—diarrhea, weight loss, palpitations, and heat intolerance—are classic signs of thyrotoxicosis, which occurs when there is an excess of thyroid hormone, possibly due to overtreatment with levothyroxine. These symptoms indicate that the thyroid hormone dose might need adjustment.
C. Addison's Disease: This is incorrect. Addison's disease is characterized by insufficient production of adrenal hormones and would typically manifest with symptoms such as fatigue, hypotension, and hyperpigmentation, not diarrhea or heat intolerance.
D. Cushing's Disease: This is incorrect. Cushing's disease is caused by excess cortisol and would typically result in symptoms such as weight gain, high blood pressure, and a round "moon" face, rather than the symptoms described in the question.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.