Anti Emetics Flashcards

1
Q

What is emesis

A

Forceful evacuation of gastric contents

Protective physiological mechanism when something harmful is ingested

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2
Q

What region is referred to as the brain stem emetic control centre or the dorsal vagal complex

A

Brain stem in a neural network on the dorsal surface of the medulla oblongata

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3
Q

What are the three major inputs to the dorsal vagal complex causing vomiting?

A

Chemoreceptor
Vagal pathway
Vestibular pathway

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4
Q

Chemoreceptor trigger zone in emesis

A

Endogenous substances, toxins, drugs

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5
Q

Vagal pathway in emesis

A

Sensory input (pain, smell, sight, thought)
Stimuli from pharynx
Stimuli from gi tract

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6
Q

Vestibular pathway in emesis

A

Disorientating motion

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7
Q

The therapeutic approach to emesis involves…

A

Blocking the neurotransmitters involved in triggering the response

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8
Q

Describe the receptor pharmacology of emesis

A

Vomiting centre - muscarinic, histamine, neurokinin, serotonin

Vestibular pathway- histamine, muscarinic

Vagal - serotonin

Chemoreceptor- dopamine, neurokinin, serotonin

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9
Q

Chemoreceptor trigger zone receptors

A

Dopamine (d2)

Substance p/ neurokinin (NK)

Serotonin (5HT3)

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10
Q

Vagal pathway receptors (emesis)

A

Serotonin (5HT3)

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11
Q

Vestibular pathway receptors (emesis)

A

Histamine (H2)

Muscarinic (M)

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12
Q

Cyclizine

A

Anti emetic histamine receptor antagonist

Motion sickness

SE:drowsiness or sedation

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13
Q

Cinnarizine

A

Anti emetic histamine receptor antagonist

Motion wickedness, vestibular disorders eg Ménière’s disease, vertigo

SE: drowsiness, sedation

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14
Q

Promethazine

A

Anti emetic histamine receptor antagonist

Severe morning sickness in pregnancy

SE: drowsiness, sedation

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15
Q

Betahistine hydrochloride (sero)

A

Activates H receptors on blood vessels in the inner ear

Local vasodilation
Increased permeability
Reverses problem of endolymphatic hydrops

SE: gi, headache, rash, pruritus

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16
Q

Phenothiazines

A

Anti emetic dopamine receptor antagonist

Severe morning sickness

Oral, iv, suppository

Inexpensive

SE: sedative, hypotension, dystonia, dyskinesia

17
Q

Perphenazine

A

Anti emetic dopamine receptor antagonist

SE: gi, opioid induces emesis, viral gastroenteritis, uraemia.

18
Q

Prochloropromazine

A

Anti emetic dopamine receptor antagonist

SE: gi, uraemia, viral gastroenteritis, opioid induces emesis

19
Q

Metoclopramide

A

Anti emetic dopamine receptor antagonist

Penetrates blood brain barrier, increases gi motility

SE: movement disorders, fatigue, motor restlessness

20
Q

Domperidone

Motillium

A

Anti emetic dopamine receptor antagonist

Does not cross BBB.

Used for migrane and cytotoxic therapy induced emesis. Emergency contraception emesis too.

Oral/ iv/ suppository

21
Q

Anti emetic dopamine receptor antagonists have a….

A

Powerful anti emetic action.

Will antagonise muscarinic and histamine receptors too.

22
Q

Hyoscine

A

Anti emetic muscarinic receptor antagonist

Non selective

Motion sickness

Oral /patch

SE: dry mouth, blurred vision. Less sedative effects than anti histamines

23
Q

Ondansetron

A

Anti emetic serotonin receptor antagonist

Drug choice for CINV (chemotherapy) PONV (anaesthetics)

Oral, suppositories, iv, Im,

SE: gi, headaches

24
Q

Granisetron

A

Anti emetic serotonin receptor antagonist

Oral, iv.

SE; gi, headaches

25
Q

Palonosetron

A

Anti emetic serotonin receptor antagonist

Iv

SE: gi, headaches

26
Q

Tropisetron

A

Anti emetic serotonin receptor antagonist

Oral, iv

SE: gi, headaches

27
Q

Aprepitant

A

Anti emetic NK1R antagonist

Active in late phase emesis with cytotoxic drugs

Substance p antagonist
Used for CINV PONV

Oral, iv

SE: fatigue, hiccups, constipation, ringing in the ears

28
Q

Fosaprepitant

A

Pro drug of aprepitant

Anti emetic NK1 R antagonist

29
Q

Casopitant

Maropitant

A

Motion sickness

Anti emetic NK1R antagonists

30
Q

Cannabinoids used in emesis

Nabilone

A

Act as agonist of cb receptors in brain stem.
Also act via opioid receptor in CTZ

Oral

SE: drowsy, dizzy, dry mouth,

Others Marinol, dronabinol.

31
Q

Corticosteroid use in emesis

A

Dexamethasone

For vomiting caused by cytotoxic drugs
Action not known
Use in combo with dopamine/serotonin drugs

32
Q

Syrup of ipecac. (Ipecacuanha)

A

Emetic

Irritates gastric mucosa and CTZ directly

Works in 15 mins

33
Q

Apomorphine

A

Emetic

CTZ and VC

IM or SC works in 5-10 mins

34
Q

Activated charcoal

A

Most commonly used emetic

Binds to toxin