N&V

Question 1

Stimulators and Receptors

Answer 1

Chemoreceptor Trigger Zone @ Area Postrema
- D2, NK1, 5HT3
CVS, GI
- 5HT3 (visceral afferents Vagus Nerve/ CN9), stimulated by Serotonin from ECL
Vestibular system
- H1, M1

Vomiting Centre @ Medulla Oblongata

• nucleus tractus solitarius H1, M1
• vomiting output - M1 (NK1 and HT3 present too)

Question 2

Groups of N&V drugs

Answer 2

Serotonin 5HT3 blocker
Corticosteroids
NK blocker
Dopamine blocker
Muscarinic blocker
H1 blocker
Benzodiazepines

Question 3

Serotonin 5HT3 blockers

Names [2] suffix? think serotonin
MOA
Usage
AE
Metab

Name 5HT4 agonist

Answer 3

Ondansetron, Palonosetron

• Block GIT N&V 5HT3
• USAGE: for acute N&V by Chemotherapy

AE: first gen Ondansetron has Qtc risk
Hepatic metabolism

Prucalopride

Question 4

Corticosteroids

Answer 4

Dexamethasone

MOA for antiemetic unknown
USAGE: for delayed N&V from chemotherapy, used with Serotonin 5HT3 blocker

Question 5

NK1/ Substance P blocker

MOA
Usage
Metab

Answer 5

Aprepitant - aPPT

• NK1 @ CTZ, Area Postrema
  USAGE: tgt w CS, and 5HT3 blockers

Metab by CYP

Question 6

Dopamine Blocker - think dopamine

MOA
AE

Answer 6

Metoclopramide, substituted benzamide

• D2 at CTZ

AE: Extra-pyramidal side effects EPS Parkinsonian symptoms from too little dopamine

• increase prolactin (controlled by dopamine)
• chronic upregulates D2 receptors, then permanent uncontrolled limb movement

Question 7

Muscarinic Antagonist

Locations
AE

Answer 7

Scopolamine/Hyoscine (nonselective M blocker)

Vomitting Centre NTS
Vestibular Nuclei
- use for motion sickness

AE: parasympatholytic: dry mouth, constipation, blurred vision

Note both scopolamine and atropine are anti parasymp drugs but Scopolamine can cross BBB

Question 8

Mixed M1, H1 blocker

Answer 8

Diphenhydramine - 1st gen AH
(DP like 2 functions both H1 Mi, hydra from H)

H1, M1 at Vomitting Center and Vestibular

USE: motion sickness
AE: sedative - H1 CNS crossing BBB, Parasympatholytic

M 1 - Saliva and GI
Note Cimetidine and Famotidine are acid blockers

Question 9

Anti-psychotics

Answer 9

Mixed Dopamine, Muscarinic, Histamine receptor blockers

• Dopamine at CTZ
• Muscarinic at Vestibular and Vomiting center

Prochlorperazine, Promethazine, Olanzapine

AE: Main concerns of EPS for dopamine and Sedative for H1

Question 10

Benzodiazepines/ Tranquilizers lol

Answer 10

Lorazepam, Diazepam;

Bind to GABA, increase Cl conductance, decrease anxiety
- prevent vomiting by anxiety

AE: sedative, respi depression

Question 11

General combination for acute and delayed N&V

Answer 11

Acute: 5HT3 + CS + NK1/DOP (dopamine)
Delayed: CS + NK1/DOP