NU 578 Spring 2017 Unit 4 Exam Questions and Correct Answers (Already Graded A+)
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NU 578
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NU 578 Spring 2017 Unit 4 Exam Questions and Correct Answers (Already Graded A+)
What is the vomiting center? - Answer A nucleus of neurons located in the medulla oblongata.
What are direct-acting stimuli for the vomiting center? - Answer Signals from the cerebral cortex (anticipation or ...
NU 578 Spring 2017 Unit 4 Exam
Questions and Correct Answers
(Already Graded A+)
What is the vomiting center? - Answer ✔ A nucleus of neurons located in the medulla
oblongata.
What are direct-acting stimuli for the vomiting center? - Answer ✔ Signals from the
cerebral cortex (anticipation or fear), signals from sensory organs (upsetting sights,
noxious odors, or pain), and signals from the vestibular apparatus of the inner ear.
What are indirect-acting stimuli for the vomiting center? - Answer ✔ First active the
chemoreceptor trigger zone (CTZ) which in turn activates the vomiting center. CTZ
activation occurs by signals from the stomach and small intestine traveling along vagal
afferents and by the direct action of emetogenic compounds (anticancer drugs, opioids,
ipecac) that are carried to the CTZ in the blood.
Receptors involved in the emetic response - Answer ✔ Serotonin, glucocorticoids,
substance P, neurokinin, dopamine, acetylcholine, and histamine.
Ondansetron [Zofran, Zofran ODT, Zuplenz] - Answer ✔ First serotonin receptor
antagonist approved for CINV. Benefits derive from blocking type 3 serotonin receptors
(5-HT3 receptors) located in the CTZ and on afferent vagal neurons in the upper GI
tract. Most common side effects are headache, diarrhea, and dizziness. Important side
effects is prolonged QT interval which poses a risk of torsades de pointes. Since it does
not block dopamine receptors it does not cause the extrapyramidal effects seen with
antiemetic phenothiazines.
Glucocorticoids - Answer ✔ Methylprednisolone and Dexamethasone are commonly
used to suppress CINV. They are effective alone and in combination with other
antiemetics.
Substance P/Neurokinin1 Antagonist - Answer ✔ Aprepitant [Emend] and Fosaprepitant
both block neurokinin1-type receptors (for substance P) in the CTZ.
Aprepitant - Answer ✔ Approved for preventing postoperative nausea and vomiting and
CINV. MOA is blockade of neurokinin1-type receptors (for substance P) in the CTZ. Can
enhance responses when combined with other antiemetic drugs. Has a prolonged
, duration of action, and hence can prevent delayed CINV away well as acute CINV. Must
be combined with other antiemetics like glucocorticoid and a serotonin antagonist since
it is only moderately effective. Absorbed in the presence and absence of food. Plasma
levels peak after 4 hours and drug undergoes extensive hepatic metabolism mainly by
CYP34A. AE are more apparent when combined with ondansetron and dexamethasone
and are fatigue and asthenia, hiccups, dizziness, and diarrhea. May also cause liver
injury (elevated aminotransferases). Substrate for, inhibitor of, and inducer of CYP34A.
Fosaprepitant - Answer ✔ An intravenous prodrug that undergoes rapid conversion in
the body. Indicated only for preventing CINV. For prevention of CINV it is used as a
substitute but only for the first dose in the 3 dose regimen. Can also cause pain and
induration at the infusion site and other AE.
Benzodiazepines - Answer ✔ Lorazepam [Ativan] is used in combination regimens to
suppress CINV. Has three principal benefits: sedation, suppression of anticipatory
emesis, and production of anterograde amnesia. Lorazepam may help control
extrapyramidal reactions caused by phenothiazine antiemetics.
Phenothiazines - Answer ✔ Dopamine Antagonists suppress emesis by blocking
dopamine2 receptors in the CTZ. Reduce emesis associated with surgery, cancer
chemotherapy, and toxins. AE include extrapyramidal reactions, anticholinergic effects,
hypotension, and sedation.
Promethazine [Phenergan] - Answer ✔ Most widely used antiemetic in young children,
despite its adverse side effects (respiratory depression and local tissue injury).
Contraindicated in children younger than age 2 and used with caution in children older
than 2.
Butyrophenones - Answer ✔ Haloperidol [Halodol] and Droperidol [Inapsine] are used
as antiemetics. They suppress emesis by blocking dopamine2 receptors in the CTZ. Are
effective against postoperative nausea and vomiting, and emesis caused by cancer
chemotherapy, radiation therapy, and toxins. Potential side effects are extrapyramidal
reactions, sedation, and hypotension. Droperidol may pose a risk of fatal dysrhythmia
owing to prolongation of the QT interval.
Metoclopramide - Answer ✔ Prokinetic Agent. Suppresses emesis through blockade of
dopamine receptors in the CTZ. The drug can suppress postoperative nausea and
vomiting as well as emesis caused by anticancer drugs, opioids, toxins, and radiation
therapy.
Cannabinoids - Answer ✔ Dronabinol [Marinol] and Nabilone [Cesamet] are related to
marijuana and approved for suppressing CINV. MOA is unknown but likely results from
activating cannabinoid receptors in and around the vomiting center. Because of their
psychotomimetic effects and abuse potential they are considered second-line drugs for
CINV, and should be reserved for patients who are unresponsive to or intolerant of
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