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Nausea:

The unpleasant feeling that often precedes vomiting.
Emesis (vomiting):
Forcible emptying of gastric, and occasionally, intestinal contents.



Antiemetic agents are used to relieve nausea and vomiting.

Antiemetic Drug Classes
Anticholinergic
Antihistamines
Neuroleptic
Prokinetic
Serotonin Blockers
Tetrahyrocannabinol (THC)

Anticholinergic Drugs
-Scopolamine- Transdermal Patch
It it used to dry GI secretions and reduce smooth muscle spasms &
-for nausea, vomiting, and motion sickness
-also to dry secretions before surgery
Side Effects:
Dizziness, drowsiness, blurred vision, dry mouth, rash

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Antihistamine Drugs-Meclizine (Antivert, Bonine, Meni-D)These drugs block H1 receptors ins the same areas as anticholinergics, so they work in the same way
They are used for motion sickness, sedation, rhinitis, allergies, nausea, vomoting, and a nonproductive cough.
Side Effects:Dizziness, drowsiness, confusion, dry mouth

Neuroleptic Drugs
-Prochlorperazine (Compazine), Promethazine (Phenergan)These drugs block the Dopamine receptors on the CTZ; desensitizes CTZ to signals it receives from the body.
They also have anticholinergic effects.
They are primarily used for antipsychotic effects, they are also used for intractable hiccups, nausea, and vomiting.
Side Effects:Orthostatic hypotension, Akathisia, dystonia, and headache
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Prokinetic Drugs
-Metoclopramide (Reglan)Primary action: it stimulates peristalsis in GI tract which promotes gastric emptying. It also blocks Dopamine receptors on the CTZ which desensitizes CTZ to signals it receives.
Again, these drugs have anticholinergic effects.
They are used fro delayed gastric emptying, GERD, nausea, and vomiting.
Side Effects:Hypotension, sedation, headache, dry mouth, and Tartive Dyskinesia

Serotonin Blockers-Ondansetron (Zofran)This class blocks serotonin receptors located in the GI tract, CTZ, and VC.It is used for nausea and vomiting associated with:
  • Chemotherapy
  • Post operative states
  • Hyperemesia in pregnancy
Side Effets:
Headache, bronchospasms

Tetrahydocannabinol (THC)
-Dronabinol (Marinol), Medical Marijuana
Mechanism of action: major psychoactive substance in marijuana, inhibitory effects on the reticulaer formation, thalamus, cerebral cortex.
The alteration in mood and perceptions of surroundings relieve nausea.
These drugs are used for nausea associated with cancer treatment and to facilitate weight gain in AIDS and anorexia

Side Effects:
severe drowsiness


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Many of these agents cause severe drowsiness so warn patients about driving or performing any hazardous tasks.
QUIZ
1). Which classification on antiemetic drugs causes a rash?
2). Which class is primarily used for antipsychotic effects but can be used for intractable hiccups?
3). Which drug is used to treat hyperemesis during pregnancy?
4). What is the primary action of Reglan?
5). Many antiemetic drugs cause ___?
6). Which drug class has the side effect of Tartive Dyskenesia?

Answers: 1). anticholinergics, 2). neuroleptics, 3). Zofran, 4). to stimulate peristalsis in GI tract, 5). severe drowsiness, 6). prokinetics

Reference:
Lilley, L., Harrington, S., & Snyder, J. (2011). Pharmacology and the nursing process. (6th ed.).
St. Louis: Mosby