Antiemetics

Question 1

ANTIEMETICS

Answer 1

CTZ- the area postrema is the location chemoreceptor trigger zone. It is present outside the blood brain barrier and responds to stimuli in the systemic circulation and CSF.
The main receptor present is the 5-HT3 receptor and D2 receptor

Vomiting center- present on the medulla its main receptor is muscarinic and NK1 receptor

Question 2

5-HT3 receptor(serotonin) antagonists:

EXAMPLES

Answer 2

Ondansetron
Palonosetron
Dolasetron

Question 3

Serotonin syndrome

Answer 3

is a group of symptoms that may occur with the use of certain serotonergic medications or drugs. Symptoms in mild cases include high blood pressure and a fast
heart rate; usually without a fever. Symptoms in moderate cases include high body temperature, agitation, increased reflexes, tremor, sweating, dilated pupils,
In severe cases body temperature can increase to greater than 41.1 °C

Question 4

Ondansetron
Palonosetron
Dolasetron

MOA

Answer 4

● Pharmacological antagonist
● Blocks chemoreceptor trigger zone and enteric nervous system 5-HT3 receptor.
● Selective serotonin receptor (5-HT3) antagonists block serotonin receptors both
peripherally on vagal nerve terminals in the gastrointestinal (GI) system and centrally in the chemoreceptor trigger zone in the area postrema of the fourth ventricle , resulting in strong antiemetic effects.

Question 5

Ondansetron
Palonosetron
Dolasetron

USE

Answer 5

● Chemotherapy
● CINV
● postoperative Vomiting

Question 6

Ondansetron
Palonosetron
Dolasetron

ADVERSE EFFECTS

Answer 6

● Headaches
● Constipation
● Flushing
● Arrhythmia
● QT prolongation
● Arrhythmias

Question 7

Ondansetron
Palonosetron
Dolasetron

Contraindications

Answer 7

● Hypersensitivity

● children under 4

Question 8

D2 Blockers: EXAMPLES

Answer 8

Metoclopramide

Domperidone

Question 9

Metoclopramide
Domperidone

MOA

Answer 9

The antiemetic action of metoclopramide is due to its antagonist activity at D2 receptors in the chemoreceptor trigger zone in the central nervous system

Question 10

Metoclopramide
Domperidone

Indications:

Answer 10

● CINV

● Pregnancy

Question 11

Metoclopramide
Domperidone

SIDE EFFECTS

Answer 11

● hyperprolactinaemia,
● Extrapyramidal effects due to decreased dopaminergic ions - parkinson like symptoms
● Fatigue
● Headace
● dizziness
● hypertension,
● galactorrhea,
● restlessness
● Dyskinesia(chronic use)

Question 12

Metoclopramide
Domperidone

Contraindications

Answer 12

● pheochromocytoma
● parkinson’s disease(worsen symptoms)
● Depression
● Epilepsy
● Newborns
● recent stomach operation.

Question 13

What type of drug is aprepitant?

Answer 13

Neurokinin receptor (NK1)blocker

Question 14

Aprepitant

MOA

Answer 14

● NK-1 receptor antagonists have antinausea and anti-vomiting properties that get relayed through a central blockade in the area postrema, nucleus tractus solitarius, and visceral afferent nerves.
● NK-1 receptors mediate most of the central and peripheral effects of substance P.
● Substance P is an excitatory neurotransmitter that has a role in pain perception.
● It is among a class of neuropeptides called neurokinins.
● Its receptor, NK-1, is a G protein-coupled consisting of seven transmembrane helical
elements.
● Therefore, NK-1 receptor antagonists can prevent both central and peripheral stimulation
of vomiting centers.