10. Antiemetics Flashcards

1
Q

Which agents act on the vestibular nuclei?

A

Muscarinic receptor antagonists

H1 receptor antagonists

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2
Q

Name a muscarinic receptor antagonist

A

Hyoscine hydrobromide

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3
Q

How do muscarinic receptor antagonists work?

A

Competitive blockade of muscarinic acetylcholine receptors

  • in vestibular nuclei
  • also at CTZ
  • but also at many other parts of the body
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4
Q

What are muscarinic receptor antagonists good for?

A

People who cant take tablets
Motion sickness
Bowel obstruction

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5
Q

What are the side effects of hyoscine hydrobromide?

A

Sedation
Memory problems
Glaucoma
Dry mouth and constipation

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6
Q

How do H1 receptor antagonists work?

A

Act on vestibular nuclei

Inhibits histaminergic signals from the vestibular system to CTZ in medulla

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7
Q

What are H1 receptor antagonists good for?

A
Motion sickness
Morning sickness (promethazine)
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8
Q

Who cannot use cyclizine?

A

Little old ladies and children

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9
Q

Name some H1 receptor antagonists

A
Cyclizine
Levomepromazine
Cinnirazine
Promethazine
Diphenhydramine
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10
Q

What are side effects of H1 receptor antagonists?

A

Sedation
Excitation
Dry mouth, constipation, urinalysis retention, cardiac toxicity

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11
Q

Which drugs act on visceral afferents in the gut?

A

5HT3 receptor antagonists

D2 receptor antagonists

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12
Q

How does 5HT3 receptor an antagonist work?

A

Peripherally - reduces GI motility, reduces GI secretions

Centrally - act to inhibit the CTZ

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13
Q

Name some 5HT3 receptor antagonists?

A

Ondansetron
Granisetron
Palonosetron

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14
Q

What are the side effects of 5HT3 receptor antagonists?

A
Uncommon
Constipation
Headache
Elevated liver enzymes 
Long QT syndrome
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15
Q

Name some D2 receptor antagonists

A

Metoclopramide

Domperidone

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16
Q

What is the action of metoclopramide?

A

Increases acetylcholine at muscarinic receptors in the gut
Promotes gastric emptying
Increases peristalsis

17
Q

What are the side effects of D2 receptor antagonists?

A

Galactorrhoea via prolactin release

Extra-pyramidal effects - dystonia, Parkinsonism

18
Q

What is metoclopramide good for?

A

GORD

Ileus

19
Q

What is domperidone good for?

A

Improving lactation in breastfeeding

20
Q

What are the side effects of domperidone?

A

Sudden cardiac death - long QT and VT

Galactorrhoea

21
Q

Which D2 receptor antagonists work on the CTZ?

A

Prochlorperazine
Chlorpromazine
Levomepromazine
Haloperidol

22
Q

What is haloperidol good for?

A

Chemotherapy and palliation

23
Q

What are corticosteroids good for?

A

Perioeprative nausea and vomiting
Chemotherapy
Palliation

24
Q

Name 2 corticosteroids

A

Dexamethasone

Methylprednisolone

25
Q

What are the side effects of corticosteroids?

A

Insomnia
Increased appetite
Increase blood sugar

26
Q

Name a useful cannabinoid

A

Nabilone

27
Q

What are the side effects of nabilone?

A

Dizziness

Drowsiness

28
Q

Name some neurokinin 1 receptor antagonists

A

Aprepitant
Fosaprepitant
Netupitant

29
Q

What is the action of neurokinin 1 receptor antagonists?

A

Prevent the action of substance P at CTZ and in peripheral nerves
Boosts effects of 5HT3 receptor antagonists

30
Q

What are neurokinin 1 receptor antagonists good for?

A

Chemotherapy - particularly for delayed emesis

31
Q

What are the side effects of neurokinin 1 receptor antagonists?

A

Headache
Diarrhoea/constipation
Stevens-Johnson syndrome

32
Q

For gut problems, what is usually the order of drugs given?

A

Ondansetron and/or cyclizine

Then add dexamethasone

33
Q

What is the treatment for hyperemesis Gravidarum?

A

Promethazine or prochlorperazine
Then add metoclopramide
Then add ondansetron