Nausea And Labyrinth Disorders

Question 1

What are the causes of nausea?

Answer 1

Drugs and toxic substances
Labyrinthitis
Vestibular disorders
Motion sickness
Gut irritation 
Higher stimuli

Question 2

How does nausea and vomiting occur?

Answer 2

When the vomiting centre inside the brain is activated by input from the chemoreceptor trigger zone which contains dopamine, serotonin, histamine and muscarinic receptors

Question 3

How do antiemetic work?

Answer 3

By antagonising the receptors in the chemoreceptor trigger zone

Question 4

What are the dopamine antagonists that can be used for nausea?

Answer 4

Metoclopramide
Domperidone
Prochlorperazine
Chlorpromazine
Haloperidol, levomepromazine
Droperidol

Question 5

What are the antihistamines used for vertigo and motion sickness?

Answer 5

Cinnarizine
Cyclizine
Promethazine teoclate

Question 6

What are the antimuscarinics used for motion sickness?

Answer 6

Hyoscine hydrobromide

Question 7

What are the 5-HT3 antagonists used in chemotherapy or post operative nausea and vomiting?

Answer 7

Granisetron
Ondansetron
Palonosetron

Question 8

What are the other antiemetics used in nausea?

Answer 8

Dexamethasone - chemotherapy, post operative

Nabilone - synthetic cannabinoid, used in chemo unresponsive to other anti emetics

Aprepitant - chemotherapy. + dexamethasone, 5HT3 antagonist

Question 9

What do you use for mild nausea in the first trimester of pregnancy?

Answer 9

Nothing

Question 10

What do you use for severe vomiting and nausea in the first trimester of pregnancy?

Answer 10

Promethazine

Prochlorperazine

Metoclopramide

Question 11

What do you use for preventative post operative nausea and vomiting?

Answer 11

5HT3 receptor antagonists, droperidol, dexamethasone, phenothiazine, cyclizine

Question 12

What do you use for high risk patients for post operative nausea and vomiting?

Answer 12

Combination of two or more antiemetics from different classes

Question 13

What is the mechanism of action of metoclopramide?

Answer 13

Antagonises D2 receptors in chemoreceptor trigger zone

Also acts directly on gut to promote gastric emptying - prokinetic effect

Question 14

What is the MHRA warning for metoclopramide?

Answer 14

Risk of neurological adverse effects - restricted dose and duration of use

Question 15

What is the maximum dose of metoclopramide?

Answer 15

18+

5 days

10mg TDS

Question 16

What is metoclopramide used for?

Answer 16

Prevention of nausea and vomiting

Symptomatic treatment of nausea and vomiting

Question 17

What are the side effects of metoclopramide?

Answer 17

Acute dystonic reactions

Procyclidine aborts dystonic attacks

Question 18

What are the interactions of metoclopramide?

Answer 18

Antipsychotics- increase extrapyramidal side effects

Parkinson’s disease - exacerbates condition

Question 19

What is the mechanism of action of domperidone?

Answer 19

Antagonised D2 receptors in chemoreceptor trigger zone

Also acts directly on gut to promote gastric emptying - prokinetic effect

Question 20

What is the MHRA advice for domperidone?

Answer 20

Risk of cardiac side effects - restricted indication, new contraindications, reduced dose and duration

Question 21

What is the maximum dose for domperidone?

Answer 21

1 week

10mg TDS

Adult 12+ and over 35kg

Question 22

What is domperidone used for?

Answer 22

Symptomatic relief of nausea and vomiting

Choice antiemetic in Parkinson’s disease

Question 23

What are the cardiac side effects of domperidone?

Answer 23

QT prolongation
Ventricular arrhythmias
Sudden death

Question 24

What are the counselling points for domperidone?

Answer 24

Report signs of arrhythmias

Question 25

What are the contraindications of domperidone?

Answer 25

Impaired cardiac conduction Cardiac disease Severe liver impairment

Question 26

What are the interactions of domperidone?

Answer 26

Potent CYP34 inhibitor - amiodarone, ketoconazole, erythromycin Drugs causing QT prolongation - amiodarone, SSRIs, quinolones

Question 27

What is the mechanism of action of 5HT3 receptor antagonists?

Answer 27

Blocks HT3 receptors in the chemoreceptor trigger zone and GI tract 5HT is a key neurotransmitter released by the gut in response to emetogenic stimuli

Question 28

What are the 5HT3 receptor antagonists?

Answer 28

Granisetron Ondansetron Palonosetron - only for chemo

Question 29

What are granisetron and ondansetron used for?

Answer 29

Post operative nausea and vomiting | Chemotherapy induced nausea and vomiting

Question 30

What are the side effects of 5HT3 receptor antagonists?

Answer 30

QT interval prolongation

Question 31

What are the interactions of the 5HT3 antagonists that increase the risk of torsades de pointes with hypokalaemia?

Answer 31

``` Loop/thiazide diuretics Corticosteroids Beta agonist - salbutamol, theophylline Stimulant laxatives abuse Amphotericin B ```

Question 32

What are the interactions of the 5HT3 antagonists that increase the risk of QT interval prolongation?

Answer 32

``` Amiodarone Clarithromycin Quinine Sumatriptan Lithium Antipsychotics ```

Question 33

What are the interactions of the 5HT3 antagonists that increase the risk of serotonin syndrome?

Answer 33

5HT1a agonists Sumatriptan MAOIs SSRIs