ANTI EMETIC AGENTS

ANTIEMETIC AGENTS BY MR. BHAVESH AMRUTE( M.PHARM PHARMACEUTICAL CHEMISTRY)

1. Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.
ANTIEMETIC AND
ANTINAUSEA DRUGS

BY
Mr. Bhavesh Bharat Amrute
(M.Pharm-Pharmaceutical Chemistry)

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

3. Vomiting center (VC)
Chemoreceptor trigger zone (CTZ)
◦Both located in the brain
◦Once stimulated, cause the vomiting reflex

5. Many different mechanisms of action
Most work by blocking one of the vomiting pathways, thus
blocking the stimulus that induces vomiting

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

8. 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)

9. 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. Dimenhydrinate Diphenhydramine
Meclizine

11. 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

12. Prochlorperazine
Promethazine
Droperidol

13. 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

14. Metoclopramide

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
◦dolasetron (Anzemet)
◦granisetron (Kytril)
◦ondansetron (Zofran)
◦palonosetron (Aloxi)

16. Dolasetron
Granisetron
Palonosetron
Ondansetron

17. Tetrahydrocannabinoids
◦Major psychoactive substance in marijuana
◦Inhibitory effects on reticular formation, thalamus, cerebral cortex
◦Alter mood and body’s perception of its surroundings

18. Tetrahydrocannabinoids (cont’d)
◦dronabinol (Marinol)
◦Used for nausea and vomiting associated with chemotherapy, and
anorexia associated with weight loss in AIDS patients

Dronabinol

19. Vary according to drug used
Stem from their nonselective blockade of various receptors