antimetics Flashcards

1
Q

7 classes of antimetics

A
  1. serotonin 5-HT3 antagonists
  2. corticosteroids
  3. neurokinin receptor antagonists
  4. dopamine receptor antagonists
  5. muscarinic receptor antagonists
  6. H1 histamine receptor antagonists
  7. benzodiazepines
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2
Q

what is an example of serotonin 5 HT antagonist

A

ondansetron, granisetron

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3
Q

when and how is ondansetron administered

A

IV 30min or ORAL 1h before chemotherapy - prevent chemotherapy induced nausea & vomiting (CINV)

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4
Q

what combination enhances its efficacy

A

corticosteroid and nk1 receptor antagonist

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5
Q

MOA of serotonin 5-HT 3 antagonists

A

acts at the 5-HT3 receptor in the GIT
also prevents nausea caused by other forms of noxious GIT stimulation

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6
Q

adverse effects of serotonin 5 HT-3 antagonists

A

headache
dizziness
constipation, diarrhoea
small risk of cardiac arrhythmia

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7
Q

what is the risk of using ondansetron in early pregnancy

A

small risk of orofacial malformations

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8
Q

what are examples of corticosteroids used for CINV

A

dexamethasone, methylprednisolone

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9
Q

adverse effects of using corticosteroids

A

higher dose or longer use (> 2 weeks) may cause iatrogenic cushing syndrome:
hyperglycaemia
GERD

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10
Q

what is an example of dopamine receptor antagonists

A

metoclopramide

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11
Q

what is the MOA of metoclopramide

A

dopamine (esp D2) receptor antagonism @ chemoreceptor trigger zone
also used as pro kinetics to stimulate GI motility

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12
Q

what are the adverse effects associated with metoclopramide

A

EPSE!!!
- parkinsonism (tremor, bradykinesia, restlessness)
- elderly are more susceptible
- long term use can lead to tardive dyskinesia

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13
Q

what are the options for treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have low emetogenic risk?

A

5 HT-3 receptor antagonists OR dexamethasone OR dopamine receptor antagonists

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14
Q

What are the recommended options for the treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have moderate emetogenic risk (other than carboplatin)?

A

5-HT3 receptor antagonist AND dexamethasone

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15
Q

What are the recommended options for the treatment of acute nausea and vomiting induced by a chemotherapy regimen expected to have a high emetogenic risk or carboplatin?

A

5-HT3 receptor antagonist AND dexamethasone AND neurokinin NK1 receptor antagonist

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16
Q

what are examples of neurokinin receptor antagonists

A

aprepitant (oral)
fosaprepitant (IV)

17
Q

what is the MOA of neurokinin receptor antagonists

A

acts at the neurokinin 1 receptor in area postrema (trigger zone for emesis)

18
Q

what are the adverse effects associated with the use of neurokinin receptor antagonists

A

common s/s: fatigue, hiccups, diarrhoea, constipation
severe: peripheral neuropathy

concerning if metabolised by cyp3a4:
- interacts with other chemotherapeutic agents (eg docetaxel and etoposide)
- drugs that inhibit cyp3a4 may influence plasma levels - ketoconazole, clarithomycin

19
Q

which class of drugs are not effective to prevent DELAYED nausea and vomiting

A

5 HT-3 receptor antagonists

20
Q

classes of drugs that can be used to prevent delayed nausea and vomiting

A

dexamethasone
metoclopramide
aprepitant
olanzapine

21
Q

Name THREE examples of mixed dopamine, muscarinic and/or histamine receptor antagonists

A
  • Phenothiazines: prochlorperazine, promethazine
    Dopamine, muscarinic & histamine receptor antagonism
  • Butyrophenones: droperidol
    Dopamine receptor antagonism and weak histamine receptor antagonism
  • Atypical antipsychotic: olanzapine
    Dopamine, muscarinic & histamine receptor antagonism
    Also 5-HT3 receptor antagonism
22
Q

what are the adverse effects associated with mixed dopamine, muscarinic and/or histamine receptor antagonists

A

sedative
EPSE
hypotension
** for droperidol - prolonged QT interval

23
Q

Name ONE example of a benzodiazepine used to manage anticipatory nausea and vomiting.

A

Lorazepam, diazepam

24
Q

MOA of benzodiazepines

A

binds to allosteric site on GABA receptors
anxiolytic
reduces anticipatory vomitting

25
adverse effects associated with benzodiazepines
sedative additive effects with CNS depressants eg antidepressants, alcohol and opoids - causing resp depression on overdose
26
who should avoid benzodiazepines and why?
pregnant women esp during first trimester, may cause risk of cleft palate
27
which drugs are effective in preventing motion sickness
Scopolamine (also known as hyoscine), diphenhydramine hyoscine - muscarinic receptor antagonists diphenhydramine - mixed h1 antihistamine and muscarinic receptor antagonists
28
adverse effects of using scopolamine
anticholinergic dry mouth, blur vision sedation & confusion **High incidence of adverse effects when given orally therefore often administered by transdermal patch
29
what are examples of mixed h1 antihistamine and muscarinic receptor antagonists
cinnarazine and diphenhydramine
30
adverse effects of using diphenhydramine/cinnarizine
sedative dry mouth, constipation and blur vision
31
pharmacotherapy for nausea and vomiting during pregnancy
pyridoxine (vit B6) supplements doxylamine - if pyridoxine is not sufficient