Anti Emetics

Question 0

What are the three pathways of emesis?

Answer 0

Chemoreceptor trigger zone
Vagal pathway
Vestibular pathway

Question 1

Where is emesis controlled and centralized?

Answer 1

In the brain stem

Question 2

What is the chemoreceptors trigger zone related to?

Answer 2

Endogenous substances/toxins/drugs

Question 3

What is the bagel pathway related to?

Answer 3

Sensory input - pain, smell, sight, thought. Stimuli from the pharynx and stimuli from the GI tract.

Question 4

What is connected to the vestibular pathway?

Answer 4

Disorientating motion

Question 5

Which is the main site of action of anti - emetic drugs?

Answer 5

The chemoreceptor trigger zone

Question 6

Which side of the blood brain barrier is the chemoreceptor zone?

Answer 6

The blood side

Question 7

Cyclizine, cinnarizine, promethazine are all…

Answer 7

H1 antagonists

Question 8

When would you use cyclizine?

Answer 8

Motion sickness

Question 9

When would you use cinnarizine?

Answer 9

Motion sickness and vestibular disorders eg vertigo

Question 10

When would you use promethazine?

Answer 10

Severe morning sickness

Question 11

What are some side effects of H1 receptor antagonists?

Answer 11

Drowsiness and sedation

Question 12

Which pathways do H1 receptor antagonists work on?

Answer 12

All 3

Question 13

What type of anti emetic is betahistine hydrochloride?

Answer 13

H3 agonist

Question 14

Describe the mode of action of betahistine hydrochloride

Answer 14

Local vasodilation
Increased permeability
Reverses the underlying problem of endolymphatic hydrops

Question 15

Hyoscine, scopolaimine

Answer 15

Anti emetic Muscarinic receptor antagonists.
Non selective
General purpose
Motion sickness - drug of choice
Oral and or transdermal patch
Side effects - dry mouth, blurred vision
Less sedative actions than anti histamines

Question 16

Which pathways do muscarinic receptor antagonists work on?

Answer 16

All 3

Question 17

Phenothiazinez

Answer 17

Severe morning sickness in pregnancy
Blocks histamine and mAch receptors
Oral, I,v or suppository.
Side effects - sedative, hypotension, dystopia, dyskinesia.

Question 18

Where do D2 receptors have a strong representation?

Answer 18

In the CTZ

Question 19

Metoclopramide

Answer 19

D2 receptor antagonist 
Penetrates bbb
Acts on GIT increasing GI mobility 
Oral, I.v, I.m
Side effects - movement disorders (children), fatigue, motor restlessness, spasmodic torticolis, menstruation disorders

Question 20

Domperidone (motilium)

Answer 20

D2 receptor antagonist
Does not penetrate bbb
Reduced effectiveness but reduced side effects
Migraine and cytotoxic induced emesis, emesis due to emergency hormonal contraception.
Oral, I.v, suppositories.

Question 21

Which pathways do D2 receptor antagonists work?

Answer 21

Chemoreceptor and vagal

Question 22

Ondanesetron

Answer 22

5HT3 antagonist
Drug of choice for chemo, anaesthetics, radiation.
Oral, suppositories, I.v, I.m
Side effects - GI disturbances, headache

Question 23

Where do 5HT3 antagonists work?

Answer 23

Brain stem
Chemoreceptor trigger zone
Vagal pathway

Question 24

Aprepitant

Answer 24

Substance P antagonist
Used for chemo and anaesthetic sickness
Oral or I.v
Side effects - fatigue, listlessness, constipation/diarrhoea, loss of appetite, hiccups.

Question 25

Fosaprepitant

Answer 25

Pro drug of aprepitant

Question 26

Maropitant

Answer 26

Used for motion sickness

Question 27

Nabilone

Answer 27

Cannabinoid
Chemo sickness
Mimetic of main chemical component of cannabis
Chronic pain management
Oral admin
Side effects - drowsiness, dizziness, dry mouth, mood changes.

Question 28

Dexamethasone

Answer 28

Corticosteroid
Chemo sickness
Used in combo with D2 or 5HT antagonists

Question 29

What are the therapeutic uses of emetics?

Answer 29

Poisonous substance ingested
Drug overdose
Alcohol intoxication

Question 30

What are emetics not used for?

Answer 30

Ingestion of corrosive substances
CNS stimulant, morphine overdose
Kerosene poisoning

Question 31

Syrup if ipecac (ipecacuanha)

Answer 31

Emetic
2 alkaloids, emetine and cepheline
Oral admin
Irritates GI mucosa and activates CTZ directly

Question 32

Apomorphine

Answer 32

Emetic
Directly stimulates CTZ and VC
IM or SC

Question 33

Activated charcoal

Answer 33

Commonly used - binds to toxins