Anti-emetics Flashcards

1
Q

What are the general indications for anti-emetics?

A

Nausea and vomiting

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2
Q

What are the types of anti-emetics?

A
  • H1 receptor antagonists
  • 5-HT3 receptor antagonists
  • D2 receptor antagonists
  • Phenothiazines
  • Hyoscine (anti-muscarinic)
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3
Q

What are some examples of H1 receptor antagonists?

A
  • Cyclizine

- Promethiazine

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4
Q

How do H1 receptor antagonists act as anti-emetics?

A

Block histamine (H1) and acetylcholine receptors in the chemoreceptor trigger zone

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5
Q

What are some examples of 5-HT3 receptor antagonists?

A

Ondansetron

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6
Q

How does ondansetron exert its anti-emetic effects?

A

Unknown

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7
Q

What are some examples of D2 receptor antagonists?

A
  • Metoclopramide

- Domperidone

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8
Q

How do D2 receptor antagonists act as anti-emetics?

A

Inhibit dopaminergic stimulation on the chemoreceptor trigger zone

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9
Q

What are some examples of phenothiazines?

A
  • Prochlorperazine

- Chlorpromazine

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10
Q

How do phenothiazines act as anti-emetics?

A

Block a variety of receptors that stimulate the chemoreceptor trigger zone

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11
Q

How does hyoscine act as an anti-emetic?

A

Exerts a spasmolytic action on the smooth muscle of the gastrointestinal biliary and genitourinary tracts and has a peripheral anticholinergic effect on the visceral wall

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12
Q

What anti-emetic is best for drug-induced vomiting?

A

Cyclizine

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13
Q

What anti-emetic is best for vomiting in pregnancy?

A

Promethiazine

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14
Q

What anti-emetic is best post-operatively?

A

Hyoscine

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15
Q

What anti-emetic is used for obstruction?

A

Metoclopramide

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16
Q

What anti-emetic is best for motion sickness?

A

Hyoscine

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17
Q

How can anti-emetics be administered?

A
  • PO
  • IV
  • IM
  • PR
18
Q

When should phenothiazines and dopamine receptor antagonists be avoided?

A

In Parkinson’s disease

Because of increased risk of extra-pyramidal side effects

19
Q

When is domperidone contraindicated?

A
  • In people with underlying cardiac or hepatic impairment
  • In people on medications that inhibit CYP3A4

Due to cardiac side effects

20
Q

What caution should be taken with metoclopramide?

A

Only use for up to 5 days

21
Q

Why should metoclopramide only be used for up to 5 days?

A

It is associated with severe neurological adverse effects

22
Q

What monitoring may be required for patients on 5HTs antagonists or phenothiazines?

A

ECG to look for prolonged QT

23
Q

Can anti-emetics be used in combination?

A

Should be avoided

24
Q

Which anti-emetics should metoclopramide not be prescribed alongside?

A
  • Ondansetron

- Cyclizine

25
Q

What anti-emetics should cyclizine not be prescribed alongside?

A
  • Metoclopramide

- Domperidone

26
Q

What medications can cyclizine interact with?

A
  • Opioids (increases sedation)

- Anticholinergics

27
Q

What medications does ondansetron interact with?

A
  • SSRI’s

- Enhanced action when prescribed with steroids

28
Q

What medications does metoclopramide interact with?

A
  • Effect is reduced by opioids
29
Q

What drugs can domperidone interact with?

A

Absorption can be reduced by antacids and H2 receptor antagonists

30
Q

What drugs does hyoscine interact with?

A

This is in the muscarinic antagonist cards

31
Q

What are the important side-effects of H1 receptor antagonists?

A

Drowsiness

32
Q

What are the important side-effects of phenothiazines?

A
  • Drowsiness
  • Postural hypotension
  • Prolonged QT interval
33
Q

What are the important side-effects of muscarinic antagonists?

A
  • Postural hypotension

- Dry mouth

34
Q

What are the important side-effects of 5-HT3 receptor antagonists?

A

Prolonged QT interval

35
Q

What are the important side-effects of D2 receptor antagonists?

A

Extrapyramidal side-effects

36
Q

What anti-emetics can cause headache, constipation/diarrhoea?

A

Several types

37
Q

What patient counselling should be given to patients on anti-emetics?

A
  • Indication
  • Side-effects and consequences
  • Anti-emetic can be changed if no relief
38
Q

What are the most important side-effects to warn patients about with anti-emetics?

A
  • Postural hypotension
  • Dizziness
  • Extrapyramidal side-effects
39
Q

What can be the consequences of anti-emetics causing dizziness and postural hypotension?

A
  • Falls
  • Unable to drive
  • Unable to operate machinery
40
Q

What are some extrapyramidal side-effects caused by D2 receptor antagonists?

A
  • Tremor
  • Bradykinesia
  • Acute dystonia
  • Akathasia
  • Tardive dyskinesia
  • Parkinsonism
41
Q

What patient counselling is required with anti-emetics?

A
  • Indication and side effects
  • Impairment of function
  • Extrapyramidal side effects
  • Changing anti-emetic if no relief