git - drugs for nausea and vomiting

Question 1

name 7 classes of drugs for nausea and vomiting

Answer 1

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

Question 2

treatment for acute nausea and vomiting induced by a chemo w low emetogenic risk

Answer 2

5-HT3 OR dexamethasone OR dopamine receptor antagonist

Question 3

treatment for acute nausea and vomiting induced by a chemo w moderate emetogenic risk

Answer 3

5-HT3 AND dexamethasone

Question 4

treatment for acute nausea and vomiting induced by a chemo w high AC emetogenic risk/carboplatin

Answer 4

5-HT3 AND dexamethasone AND NK1

Question 5

treatment for acute nausea and vomiting induced by a chemo w high non-AC emetogenic risk

Answer 5

5-HT3 AND dexamethasone AND NK1 AND olanzapine

Question 6

name 3 eg of 5-HT3 antagonist

Answer 6

1. ondansetron
2. granisetron
3. palonosetron

Question 7

moa of 5-HT3 antagonist

Answer 7

• act on 5-HT3 receptors in GIT → block transmission of signals of distension and noxious stimuli from GIT to CNS

Question 8

clinical use of 5-HT3 antagonist

Answer 8

• prevent acute chemo-induced vomiting - given 30 min (IV)/1h (oral) before chemo
• prevent nausea caused by other noxious GIT stimulation (eg. small bowel obstruction)

Question 9

adverse effects of 5-HT3 antagonist

Answer 9

• headache, dizziness, drowsiness
• constipation/diarrhoea
• DDI (CYP450)
• risk of cardiac arrhythmia (QT prolongation)

Question 10

adverse effects of ondansetron

Answer 10

risk of orofacial malformations in foetus if taken in early pregnancy

AVOID in 1st trimester

Question 11

name 2 corticosteroids

Answer 11

1. dexamethasone
2. methylprednisolone

Question 12

moa of corticosteroids

Answer 12

• combined w 5-HT3 to prevent acute and delayed n&v in pts on moderately to highly emetogenic chemotherapy

Question 13

adverse effects of corticosteroids

Answer 13

higher doses/longer-term use (> 2 weeks) can cause iatrogenic Cushing’s syndrome

Question 14

name 1 dopamine receptor antagonists

Answer 14

metoclopramide

Question 15

moa of dopamine receptor antagonists

Answer 15

• dopamine receptor (esp D2) antagonism at chemoreceptor trigger zone
• prokinetic effect to stimulate GI motility

Question 16

adverse effects of dopamine receptor antagonists

Answer 16

• extrapyramidal symptoms
  
  • Parkinsonian symptoms
  • irreversible tardive dyskinesia (w LT use)
• elevated prolactin
  
  • galactorrhea, menstrual disorders (females)
  • gynaecomastia, impotence (males)

Question 17

name 2 NK1 receptor antagonists and their mode of administration

Answer 17

1. aprepitant (oral)
2. fosaprepitant (IV)

Question 18

moa of NK1 receptor antagonists

Answer 18

act on NK1 receptors in chemoreceptor trigger zone of area postrema

Question 19

use of NK1 receptor antagonists

Answer 19

• used with 5-HT3 and corticosteroid to prevent acute/delayed n&v caused by chemo

Question 20

adverse effects of NK1 receptor antagonists

Answer 20

• common: fatigue, hiccups, diarrhoea/constipation
• severe: peripheral neuropathy, blood dyscrasia
• DDI (CYP3A4)

Question 21

treatment for delayed nausea and vomiting induced by oxaliplatin/anthracycline/cyclophosphamide

Answer 21

dexamethasone

Question 22

treatment for delayed nausea and vomiting induced by carboplatin

Answer 22

aprepitant

Question 23

treatment for delayed nausea and vomiting induced by chemo w high AC emetic risk

Answer 23

dexamethasone OR aprepitant

Question 24

treatment for delayed nausea and vomiting induced by chemo w high non-AC emetic risk

Answer 24

dexamethasone AND olanzapine/metoclopramide/aprepitant

Question 25

name 3 classses of antipsychotics

Answer 25

1. phenothiazines 2. butyrophenones 3. atypical antipsychotics

Question 26

name 2 eg of phenothiazines

Answer 26

1. promethazine 2. prochlorperazine

Question 27

moa of phenothiazines

Answer 27

- dopamine antagonism - muscarinic antagonism - antihistamine

Question 28

name 1 butyrophenone

Answer 28

droperidol

Question 29

moa of butyrophenones

Answer 29

- dopamine antagonism - antihistamine

Question 30

name 1 atypical antipsychotic

Answer 30

olanzapine

Question 31

moa of atypical antipsychotics

Answer 31

- dopamine antagonism - muscarinic antagonism - antihistamine - 5-HT3 receptor antagonism

Question 32

adverse effects of antipsychotics

Answer 32

- sedative - extrapyramidal syndrome (Parkinsonism) - hypotension - QT prolongation

Question 33

name 2 eg of benzodiazepines

Answer 33

1. lorazepam 2. diazepam

Question 34

moa of benzodiazepines

Answer 34

- bind to allosteric site of GABA-A receptors → increases chloride conductance - reduce anticipatory vomiting, vomiting caused by anxiety

Question 35

adverse effects of benzodiazepines

Answer 35

- sedative - additive effect w CNS depressants (antidepressants, alcohol, opioids) → respi depression on od

Question 36

contraindication for benzodiazepine

Answer 36

- CNS depressants - pregnancy, esp 1st trimester → risk of cleft palate

Question 37

name 3 drugs used for motion sickness

Answer 37

1. hyoscine (scopolamine) 2. diphenhydramine 3. cinnarizine

Question 38

moa of hyoscine

Answer 38

muscarinic antagonist (act in vestibular system and vomiting centre)

Question 39

moa of cinnarizine and diphenhydramine

Answer 39

- H1 antihistamine - M1 antagonism

Question 40

adverse effects of drugs for motion sickness

Answer 40

- dry mouth - blurred vision - sedation - confusion

Question 41

management of n&v in pregnancy

Answer 41

- best to avoid drugs, suggest dietary changes - pyridoxine (vit B6) supplements - doxylamine (1st gen antihistamine, muscarinic antagonist)

Question 42

management of n&v in children

Answer 42

- avoid drugs, only give for persistent n&v - gastroparesis: prokinetic agents - post-op n&v: 5-HT3 - chemo-induced: 5-HT3, NK1