Nausea & vomiting Flashcards
What are the 7 groups of antiemetic drugs?
- Serotonin 5-HT3 antagonists
- Corticosteroids
- Neurokinin receptor antagonists
- Dopamine receptor antagonists
- Muscarinic receptor antagonists
- H1 histamine receptor antihistamines
- Benzodiazepines
What are the 4 sites that an trigger the vomiting reflex?
- Chemoreceptor trigger zone in the brain
- GIT
- Vestibular system
- Higher centres in the CNS
What is the treatment for chemotherapy regiment with LOW emetogenic risk?
Serotinin 5-HT3 receptor antagonist (first-line) OR
Dexamethasone OR
Dopamine D2 receptor antagonist
Name 2 examples of serotonin 5-HT3 antagonists
Ondansetron
Granisetron
Granisetron longer half-life; better for cancer patients
MOA of ondansetron?
Act at 5-HT3 receptors primarily in the GIT
Which antiemetics increase risk of cardiac arrhythmias?
Serotonin 5-HT3 antagonists & droperidol
May prolong QT interval
What group of patients is ondansetron contraindicated in?
Cardiac abnormalities
Early pregnancy
Patients on drugs that prolong QT interval
Ondansetron increases risk of orofacial malformations in early pregnancy
Fluoroquinolones, macrolides, azoles, antidepressants, anti-arrhythmia medications
What can 5-HT3 antagonists be combined with to increase antiemetic effect?
5HT3 antagonist + corticosteroid (dexamethasone) + NK1-receptor antagonist
When is ondansetron given to prevent N&V in patients undergoing chemo?
30min before chemo; IV
Name an example of a D2 receptor antagonist
Meteoclopramide
MOA of metoclopramide?
Blocks dopamine D2-receptors in the CTZ
Chemoreceptor trigger zone
What are the side-effects of long-term metoclopramide use?
Irreversible tardive dyskinesia
Wrong movements like twitching of the face
Which antiemetic causes Parkinsonian symptoms?
Metoclopramide
Adverse effects of metoclopromide?
Parkinsonian symptoms
Irreversible tardive dyskinesia
Elevated prolactin
Elevated prolactin causes manboobs, impotence, galactorrhea
What is the treatment for chemotherapy regiment with HIGH emetogenic risk?
5-HT3 receptor antagonist + corticosteroid (dexamethasone) + neurokinin 1-receptor antagonist
Name 2 examples of NK1-receptor antagonists
Aprepitant (PO)
Fosaprepitant (IV)
MOA of NK1-receptor antagonists?
Blocks neurokinin 1 receptors at the CTZ
Chemoreceptor triggerzone
Severe adverse effects of NK1-receptor antagonists?
Peripheral neuropathy
Blood dyscrasias
What is the treatment for delayed N&V?
Combinations of:
- Dexamethasone
- Metoclopromide
- Aprepitant
- Olanzapine (can be considered)
Name 3 antipsychotics
Prochlorperazine
Promethazine
Olanzapine
Droperidol
MOA of antipsychotics?
Dopamine (CTZ) + muscarinic + histamine antagonism (vestibular system + vomiting centre)
What antiemetic should be given for anticipatory N&V?
N&V due to anxiety
Benzodiazepines (Lorazepam, diazepam)
Name 2 examples of benzodiazepines
Lorazepam
Diazepam
MOA of benzodiazepines?
Binds to allosteric site on GABA receptors increasing chloride conductance; anxiolytic
What group of patients should avoid taking benzodiazepines?
Pregnant women
Risk of cleft palate
What antiemetics should be taken for motion sickness?
- Hyoscine; mACh-receptor antagonist
- Cinnarizine; H1 antihistamine & mACh-receptor antagonist
Both act on vestibular system + vomiting centre
What is the prodrug formulation of aprepitant?
Fosaprepitant
Where are the 5-HT3 receptors found?
CTZ
Visceral afferents (in GIT)
Where are the H1 histamine & mACh receptors found?
Vestibular nuclei
Vomiting centre
