Chapter 52 Antiemetic and Antinausea Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Transcript of Chapter 52 Antiemetic and Antinausea Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Chapter 52
Antiemetic and Antinausea Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Definitions
2Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Vomiting center (VC) Chemoreceptor trigger zone (CTZ)
Both located in the brain Once stimulated, cause the vomiting reflex
Vomiting Center and Chemoreceptor Trigger Zone
3Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
4Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Anticholinergic drugs Antihistamines (histamine 1 [H1] receptor
blockers) Antidopaminergic drugs Prokinetic drugs Serotonin blockers Tetrahydrocannabinoids
Antiemetics and Antinausea Drugs
5Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Many different mechanisms of action Most work by blocking one of the vomiting
pathways, thus blocking the stimulus that induces vomiting
Antiemetics and Antinausea Drugs: Mechanism of Action
6Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
7Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Specific indications vary per class of antiemetics General use for each type: prevention and
reduction of nausea and vomiting
Indications
8Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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)
Mechanism of Action and Other Indications
9Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
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.Cataracts
B.Narrow-angle glaucoma
C.Presbyopia
D.Detached retina
10Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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)
Mechanism of Action and Other Indications (cont’d)
11Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Mechanism of Action and Other Indications (cont’d)
12Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Mechanism of Action and Other Indications (cont’d)
13Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
A patient is receiving a continuous tube feeding via a PEG tube. Which drug would most likely be prescribed for this patient?
A.metoclopramide (Reglan)
B.meclizine (Antivert)
C.aprepitant (Emend)
D.phosphorated carbohydrate solution (Emetrol)
14Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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)
Mechanism of Action and Other Indications (cont’d)
15Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Mechanism of Action and Other Indications (cont’d)
16Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
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.17Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Tetrahydrocannabinoids (THC) (cont’d) dronabinol (Marinol) Used for nausea and vomiting associated with
chemotherapy, and anorexia associated with weight loss in AIDS patients
Mechanism of Action and Other Indications (cont’d)
18Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
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.phosphorated carbohydrate solution (Emetrol)
B.aprepitant (Emend)
C.palonosetron (Aloxi)
D.dolasetron (Anzemet)19Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Miscellaneous Antinausea Drugs
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Vary according to drug used Stem from their nonselective blockade of various
receptors
Adverse Effects
21Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
Which group of drugs used to treat nausea does the nurse identify as most likely to cause a prolonged QTc interval?
A.Prokinetics
B.Antidopaminergics
C.Tetrahydrocannabinoids
D.Serotonin blockers
22Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Herbal Products: Ginger
23Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Classroom Response Question
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.furosemide (Lasix)
B.acetaminophen (Tylenol)
C.warfarin (Coumadin)
D.calcium supplements
24Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Assess complete nausea and vomiting history, including precipitating factors
Assess current medications Assess for contraindications and potential drug
interactions
Nursing Implications
25Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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
Nursing Implications (cont’d)
26Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
For chemotherapy, antiemetics are often given 30 to 60 minutes before chemotherapy begins
Monitor for therapeutic effects Monitor for adverse effects
Nursing Implications (cont’d)
27Copyright © 2014 by Mosby, an imprint of Elsevier Inc.