Chapter 52
ANTIEMETIC AND ANTI-NAUSEA DRUGS
DSN
Copyright © 2014 by Mosby, an imprint of Elsevier
Inc.
KEVIN DOBI, MS, APRN
Definitions
2
 Nausea
 Unpleasant feeling that often precedes vomiting
 Emesis (vomiting)
 Forcible emptying of gastric, and occasionally, intestinal
contents
 Antiemetic drugs
 Used to relieve nausea and vomiting
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Vomiting Center and Chemoreceptor Trigger
Zone
3
 Vomiting center (VC)
 Chemoreceptor trigger zone (CTZ)
 Both located in the brain
 Once stimulated, cause the vomiting reflex
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4
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Antiemetics and Antinausea Drugs
5
 Anticholinergic drugs
 Antihistamines (histamine 1 [H1] receptor




blockers)
Antidopaminergic drugs
Prokinetic drugs
Serotonin blockers
Tetrahydrocannabinoids
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Inc.
Antiemetics and Antinausea Drugs: Mechanism
of Action
6
 Many different mechanisms of action
 Most work by blocking one of the vomiting
pathways, thus blocking the stimulus that induces
vomiting
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Indications
8
 Specific indications vary per class of antiemetics
 General use for each type: prevention and
reduction of nausea and vomiting
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Mechanism of Action and
Other Indications
9
 Anticholinergic drugs (ACh blockers)
 Bind to and block acetylcholine (ACh) receptors in the
inner ear labyrinth
 Block transmission of nauseating stimuli to CTZ
 Also block transmission of nauseating stimuli from the
reticular formation to the VC
 scopolamine (Transderm-Scōp, Scopace)
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Classroom Response Question
10
The nurse is preparing to administer scopolamine to a
patient. It is most important for the nurse to
determine if the patient has a history of which
condition?
A.
B.
C.
D.
Cataracts
Narrow-angle glaucoma
Presbyopia
Detached retina
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Inc.
Mechanism of Action and
Other Indications (cont’d)
11
 Antihistamine drugs (H1 receptor blockers)
 Inhibit ACh by binding to H1 receptors
 Prevent cholinergic stimulation in vestibular and
reticular areas, thus preventing nausea and vomiting
 Also used for motion sickness, nonproductive cough,
allergy symptoms, sedation
 Examples
dimenhydrinate (Dramamine)
 diphenhydramine (Benadryl)
 meclizine (Antivert)

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Mechanism of Action and
Other Indications (cont’d)
12
 Antidopaminergic drugs
 Block dopamine receptors in the CTZ
 Also used for psychotic disorders, intractable hiccups
 Examples
prochlorperazine (Compazine)
 promethazine (Phenergan)
 droperidol: Use is controversial because of associated cardiac
dysrhythmia

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Mechanism of Action and
Other Indications (cont’d)
13
 Prokinetic drugs
 Block dopamine receptors in the CTZ
 Cause CTZ to be desensitized to impulses it receives
from the GI tract
 Also stimulate peristalsis in GI tract, enhancing
emptying of stomach contents
 Also used for gastroesophageal reflux disease (GERD),
delayed gastric emptying
 metoclopramide (Reglan)

Long-term use may cause irreversible tardive dyskinesia
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Classroom Response Question
14
A patient is receiving a continuous tube feeding via a
PEG tube. Which drug would most likely be prescribed
for this patient?
A.
B.
C.
D.
metoclopramide (Reglan)
meclizine (Antivert)
aprepitant (Emend)
phosphorated carbohydrate solution (Emetrol)
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Mechanism of Action and
Other Indications (cont’d)
15
 Serotonin blockers
 Block serotonin receptors in the GI tract, CTZ, and VC
 Used for nausea and vomiting in patients receiving
chemotherapy and for postoperative nausea and
vomiting
 Examples
dolasetron (Anzemet)
 granisetron (Kytril)
 ondansetron (Zofran)
 palonosetron (Aloxi)

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Mechanism of Action and
Other Indications (cont’d)
16
 Tetrahydrocannabinoids
 Major psychoactive substance in marijuana
 Inhibitory effects on reticular formation, thalamus,
cerebral cortex
 Alter mood and body’s perception of its surroundings,
which may help relieve nausea and vomiting
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Classroom Response Question
17
A patient with terminal cancer has not had
chemotherapy for a few weeks and has had no nausea or
vomiting since then. However, he is taking dronabinol
twice a day. The reason for the dronabinol order is to
A. prevent recurrence of the chemotherapy-induced nausea and
vomiting.
B. prevent stress ulcers.
C. improve his mood.
D. stimulate his appetite.
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Mechanism of Action and
Other Indications (cont’d)
18
 Tetrahydrocannabinoids (THC) (cont’d)
 dronabinol (Marinol)
 Used for nausea and vomiting associated with
chemotherapy, and anorexia associated with weight loss
in AIDS patients
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Classroom Response Question
19
A patient is 2 months pregnant. She comes to the clinic
complaining of severe morning sickness. She has tried
numerous non-pharmacologic measures to relieve the
morning sickness, but they have not worked. The nurse
anticipates the use of which antinausea drug?
A.
B.
C.
D.
phosphorated carbohydrate solution (Emetrol)
aprepitant (Emend)
palonosetron (Aloxi)
dolasetron (Anzemet)
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Miscellaneous Antinausea Drugs
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 phosphorated carbohydrate solution (Emetrol)
 Mint-flavored oral solution
 Used off label for treatment of morning sickness
 aprepitant (Emend)
 Used for the prevention of nausea and vomiting
associated with highly emetogenic cancer chemotherapy
regimens
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Adverse Effects
21
 Vary according to drug used
 Stem from their nonselective blockade of various
receptors
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Classroom Response Question
22
Which group of drugs used to treat nausea does the
nurse identify as most likely to cause a prolonged QTc
interval?
A.
B.
C.
D.
Prokinetics
Antidopaminergics
Tetrahydrocannabinoids
Serotonin blockers
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Herbal Products: Ginger
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 Used for nausea and vomiting, including that
caused by chemotherapy, morning sickness, and
motion sickness
 Adverse effects

Anorexia, nausea and vomiting, skin reactions
 Drug interactions
 May increase absorption of oral medications
 Increase bleeding risk with anticoagulants
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Classroom Response Question
24
A patient tells the nurse that he takes ginger almost
every day for nausea. It is most important for the nurse
to determine if the patient is taking which medication?
A.
B.
C.
D.
furosemide (Lasix)
acetaminophen (Tylenol)
warfarin (Coumadin)
calcium supplements
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Nursing Implications
25
 Assess complete nausea and vomiting history,
including precipitating factors
 Assess current medications
 Assess for contraindications and potential drug
interactions
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Nursing Implications (cont’d)
26
 Many of these drugs cause severe drowsiness;
warn patients about driving or performing any
hazardous tasks
 Taking antiemetics with alcohol may cause severe
CNS depression
 Teach patients to change positions slowly to avoid
hypotensive effects
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Nursing Implications (cont’d)
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 For chemotherapy, antiemetics are often given 30
to 60 minutes before chemotherapy begins
 Monitor for therapeutic effects
 Monitor for adverse effects
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