Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. CHAPTER 52 Antiemetic and Antinausea Drugs

2 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Definitions  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

3 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Vomiting Center and Chemoreceptor Trigger Zone  Vomiting center (VC)  Chemoreceptor trigger zone (CTZ)  Both located in the brain  Once stimulated, cause the vomiting reflex

4 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

5 Antiemetics and Antinausea Drugs: Mechanism of Action  Many different mechanisms of action  Most work by blocking one of the vomiting pathways, thus blocking the stimulus that induces vomiting

6 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

7 Indications  Specific indications vary per class of antiemetics  General use for each type: prevention and reduction of nausea and vomiting

8 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications  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 Also used for motion sickness (transdermal patch) Also used for motion sickness (transdermal patch)

9 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  Antihistamine drugs (H 1 receptor blockers)  Inhibit ACh by binding to H 1 receptors  Prevent cholinergic stimulation in vestibular and reticular areas, thus preventing nausea and vomiting  Also used for motion sickness, nonproductive cough, allergy symptoms, sedation  dimenhydrinate (Dramamine)  diphenhydramine (Benadryl)  meclizine (Antivert)

10 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  Antidopaminergic drugs  Block dopamine receptors on the CTZ  Also used for psychotic disorders, intractable hiccups  prochlorperazine (Compazine)  promethazine (Phenergan)  droperidol (Inapsine): Use is controversial because of associated cardiac dysrhythmia  Others

11 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  Prokinetic drugs  Block dopamine 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 GERD, delayed gastric emptying  metoclopramide (Reglan) Long-term use may cause irreversible tardive dyskinesia Long-term use may cause irreversible tardive dyskinesia

12 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  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  dolasetron (Anzemet)  granisetron (Kytril)  ondansetron (Zofran)  palonosetron (Aloxi)

13 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  Tetrahydrocannabinoids  Major psychoactive substance in marijuana  Inhibitory effects on reticular formation, thalamus, cerebral cortex  Alter mood and body’s perception of its surroundings

14 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action and Other Indications (cont’d)  Tetrahydrocannabinoids (cont’d)  dronabinol (Marinol)  Used for nausea and vomiting associated with chemotherapy, and anorexia associated with weight loss in AIDS patients

15 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Adverse Effects  Vary according to drug used  Stem from their nonselective blockade of various receptors

16 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Herbal Products: Ginger  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

17 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications  Assess complete nausea and vomiting history, including precipitating factors  Assess current medications  Assess for contraindications and potential drug interactions

18 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  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 position slowly to avoid hypotensive effects

19 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  For chemotherapy, antiemetics are often given 30 to 60 minutes before chemotherapy begins  Monitor for therapeutic effects  Monitor for adverse effects