git - drugs for nausea and vomiting Flashcards
name 7 classes of drugs for nausea and vomiting
- serotonin 5-HT3 antagonists
- corticosteroids
- neurokinin receptor antagonists
- dopamine receptor antagonists
- muscarinic receptor antagonists
- H1 histamine receptor antihistamines
- benzodiazepines
treatment for acute nausea and vomiting induced by a chemo w low emetogenic risk
5-HT3 OR dexamethasone OR dopamine receptor antagonist
treatment for acute nausea and vomiting induced by a chemo w moderate emetogenic risk
5-HT3 AND dexamethasone
treatment for acute nausea and vomiting induced by a chemo w high AC emetogenic risk/carboplatin
5-HT3 AND dexamethasone AND NK1
treatment for acute nausea and vomiting induced by a chemo w high non-AC emetogenic risk
5-HT3 AND dexamethasone AND NK1 AND olanzapine
name 3 eg of 5-HT3 antagonist
- ondansetron
- granisetron
- palonosetron
moa of 5-HT3 antagonist
- act on 5-HT3 receptors in GIT → block transmission of signals of distension and noxious stimuli from GIT to CNS
clinical use of 5-HT3 antagonist
- 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)
adverse effects of 5-HT3 antagonist
- headache, dizziness, drowsiness
- constipation/diarrhoea
- DDI (CYP450)
- risk of cardiac arrhythmia (QT prolongation)
adverse effects of ondansetron
risk of orofacial malformations in foetus if taken in early pregnancy
AVOID in 1st trimester
name 2 corticosteroids
- dexamethasone
- methylprednisolone
moa of corticosteroids
- combined w 5-HT3 to prevent acute and delayed n&v in pts on moderately to highly emetogenic chemotherapy
adverse effects of corticosteroids
higher doses/longer-term use (> 2 weeks) can cause iatrogenic Cushing’s syndrome
name 1 dopamine receptor antagonists
metoclopramide
moa of dopamine receptor antagonists
- dopamine receptor (esp D2) antagonism at chemoreceptor trigger zone
- prokinetic effect to stimulate GI motility
adverse effects of dopamine receptor antagonists
- extrapyramidal symptoms
- Parkinsonian symptoms
- irreversible tardive dyskinesia (w LT use)
- elevated prolactin
- galactorrhea, menstrual disorders (females)
- gynaecomastia, impotence (males)
name 2 NK1 receptor antagonists and their mode of administration
- aprepitant (oral)
- fosaprepitant (IV)
moa of NK1 receptor antagonists
act on NK1 receptors in chemoreceptor trigger zone of area postrema
use of NK1 receptor antagonists
- used with 5-HT3 and corticosteroid to prevent acute/delayed n&v caused by chemo
adverse effects of NK1 receptor antagonists
- common: fatigue, hiccups, diarrhoea/constipation
- severe: peripheral neuropathy, blood dyscrasia
- DDI (CYP3A4)
treatment for delayed nausea and vomiting induced by oxaliplatin/anthracycline/cyclophosphamide
dexamethasone
treatment for delayed nausea and vomiting induced by carboplatin
aprepitant
treatment for delayed nausea and vomiting induced by chemo w high AC emetic risk
dexamethasone OR aprepitant
treatment for delayed nausea and vomiting induced by chemo w high non-AC emetic risk
dexamethasone AND olanzapine/metoclopramide/aprepitant
name 3 classses of antipsychotics
- phenothiazines
- butyrophenones
- atypical antipsychotics
name 2 eg of phenothiazines
- promethazine
- prochlorperazine
moa of phenothiazines
- dopamine antagonism
- muscarinic antagonism
- antihistamine
name 1 butyrophenone
droperidol
moa of butyrophenones
- dopamine antagonism
- antihistamine
name 1 atypical antipsychotic
olanzapine
moa of atypical antipsychotics
- dopamine antagonism
- muscarinic antagonism
- antihistamine
- 5-HT3 receptor antagonism
adverse effects of antipsychotics
- sedative
- extrapyramidal syndrome (Parkinsonism)
- hypotension
- QT prolongation
name 2 eg of benzodiazepines
- lorazepam
- diazepam
moa of benzodiazepines
- bind to allosteric site of GABA-A receptors → increases chloride conductance
- reduce anticipatory vomiting, vomiting caused by anxiety
adverse effects of benzodiazepines
- sedative
- additive effect w CNS depressants (antidepressants, alcohol, opioids) → respi depression on od
contraindication for benzodiazepine
- CNS depressants
- pregnancy, esp 1st trimester → risk of cleft palate
name 3 drugs used for motion sickness
- hyoscine (scopolamine)
- diphenhydramine
- cinnarizine
moa of hyoscine
muscarinic antagonist (act in vestibular system and vomiting centre)
moa of cinnarizine and diphenhydramine
- H1 antihistamine
- M1 antagonism
adverse effects of drugs for motion sickness
- dry mouth
- blurred vision
- sedation
- confusion
management of n&v in pregnancy
- best to avoid drugs, suggest dietary changes
- pyridoxine (vit B6) supplements
- doxylamine (1st gen antihistamine, muscarinic antagonist)
management of n&v in children
- avoid drugs, only give for persistent n&v
- gastroparesis: prokinetic agents
- post-op n&v: 5-HT3
- chemo-induced: 5-HT3, NK1
