Gastroenterology: Pharmacology - Antiemetics

Question 1

Four afferent inputs to vomiting centre

Answer 1

1. Area postrema (CTZ)
2. Vestibular system
3. Afferent GIT nerves (5HT-3)
4. CNS (higher centres)

Question 2

Mechanism of action of ondansetron

Answer 2

5HT-3 receptor antagonist

Question 3

Mechanism of antiemetic effect of corticosteroids

Answer 3

Unknown

Question 4

Mechanism of action of aprepitant, netupitant, rolapitant

Answer 4

NK1-receptor antagonists

Question 5

Four receptors found in the vomiting centre

Answer 5

M1
H1
NK1
5HT-3

Question 6

Five antipsychotic agents with antiemetic effects

Answer 6

Prochlorperazine (Stemetil)
Promethazine (Phenergan)
Chlorpromazine (Largactil)
Olanzapine
Droperidol

Question 7

How are the antiemetic effects of antipsychotics mediated? What about olanzapine and droperidol specifically?

Answer 7

Dopamine and muscarinic blockage
Olanzapine inhibits D2 and 5HT-1C and 5HT-3 receptors
Droperidol is antidopaminergic

Question 8

Mechanism of action of metoclopramide

Answer 8

Dopamine-receptor blockage

Question 9

Four receptor types in area postrema (CTZ)

Answer 9

1. Chemoreceptors
2. D2
3. NK1
4. 5HT-3

Question 10

Mechanism of action of diphenhydramine, meclizine

Answer 10

H1 receptor antagonist