Chapter 54 Antiemetic and Antinausea drugs

Question 1

Antiemetic drugs

Answer 1

Drugs given to relieve nausea and vomiting
- Many different mechanisms of action but Most work by blocking one of the vomiting pathways, thus blocking the stimulus that induces vomiting

Question 2

Chemoreceptor trigger zone (CTZ)

Answer 2

The area of the brain that is involved in the sensation of nausea and the action of vomiting

Question 3

Emesis

Answer 3

The forcible emptying or expulsion of gastric and, occasionally, intestinal contents through the mouth (also called vomiting)

Question 4

Nausea

Answer 4

Sensation often leading to the urge to vomit

Question 5

Vomiting center (VC)

Answer 5

The area of the brain that is involved in stimulating the physiological events that lead to nausea and vomiting

Question 6

Anticholinergic drugs (ACh blockers)

Answer 6

• 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

Question 7

Antihistamine drugs (H1 receptor blockers)

Answer 7

• Inhibit ACh by binding to H1 receptors
• Prevent cholinergic stimulation in vestibular and reticular areas, thus preventing nausea and vomiting
• Include dimenhydrinate (Dinate, Gravol, Nauseatol, others), diphenhydramine (Aller-Aide, Allerdryl, Benadryl)
• Are also used for motion sickness, nonproductive cough, allergy symptoms, sedation

Question 8

Neuroleptic drugs

Answer 8

• Block dopamine receptors on the CTZ
• Include chlorpromazine (Stematal)
• Are also used for psychotic disorders, intractable hiccups

Question 9

Prokinetic drugs

Answer 9

• Block dopamine in the CTZ
• Desensitize CTZ to impulses it receives from the gastrointestinal (GI) tract
• Also stimulate peristalsis in GI tract, enhancing emptying of stomach contents
• Include metoclopramide (Apo-Metoclop or Maxalone?)
• Are also used for GERD, delayed gastric emptying

Question 10

Serotonin blockers

Answer 10

• Block serotonin receptors in the GI tract, CTZ, and VC
• Include ondansetron (Zofran)
• Are used for nausea and vomiting in patients receiving chemotherapy and for postoperative nausea and vomiting
• Most effective drug to stop nausea and vomiting

Question 11

Tetrahydrocannabinoids

Answer 11

• Are a major psychoactive substance in marijuana
• Have inhibitory effects on reticular formation, thalamus, cerebral cortex
• Alter mood and body’s perception of its surroundings
• nabilone (Cesamex)
• Are used for nausea and vomiting associated with chemotherapy and anorexia associated with weight loss in patients with acquired immune deficiency syndrome (AIDS)

Question 12

Nursing implications

Answer 12

• Assess complete nausea and vomiting history, including precipitating factors
• Many of these drugs cause severe drowsiness; warn patients about driving or performing any hazardous tasks
• Taking antiemetics with alcohol may cause severe central nervous system (CNS) depression
• Teach patients to change position slowly to avoid hypotensive effects
• When used in patients receiving chemotherapy, antiemetics are usually given 1 to 3 hours before a chemotherapy drug