General info Flashcards
Causes
Drugs and toxic substances
Labyrinthitis (inner ear infection)
Vestibular disorders
Motion sickness
gut irritation
Higher stimuli (sights, smells, emotions)
Why does N + V occur?
Occurs when the vomiting centre inside the brain is activated by input from the chemoreceptor trigger zone (CTZ).
CTZ
Located in medulla oblongata of the brainstem.
Contains dopamine, serotonin, histamine and muscarinic receptors.
General MoA - antiemetics
Antagonise the receptors in the CTZ
Chosen according to the aetiology of vomiting.
Dopamine antagonists
- Metoclopramide
- Domperidone (used in PD)
Also antipsychotics: - Prochlorperazine
- Perphenazine
- Trifluoperazine
- Chlorpromazine
- Haloperidol
- Levomepromazine
- Droperidol
Antihistamines
- Cinnarizine
- Cyclizine
- Promethazine teoclate
Antimuscarinics
- Hyoscine hydrobromide (most effective in motion sickness)
5-HT3 antagonsists
- Granisetron
- Ondansetron
- Palonosetron
Others
- Dexamethasone
- Nabilone
- Aprepitant
- Fosaprepitant
- Rolapitant
Post-op
- Chlorpromazine
- Droperidol
- Dexamethasone
- Granisetron
- Ondansetron
- Palonosetron
Vertigo
- Cinnarizine
- Cyclizine
- Promethazine teoclate
Motion sickness
- Hyoscine hydrobromide (most effective)
- Cinnarizine
- Cyclizine
- Promethazine teoclate
Chemotherapy
- Dexamethasone
- Ondansetron
- Granisetron
- Palonosetron
Palliative care
Haloperidol
Levomepromazine
Prochlorperazine
Used as a buccal tablet in migraine
Also used post-op
Nabilone
Synthetic cannabinoid
Used in chemo unresponsive to other antiemetics
Aprepitant, fosaprepitant, rolapitant
Used in chemo
Given with dexamethasone and 5-HT3
Pregnancy
1st trimester
Mild = no drug treatment
Severe
- Chlorpromazine
- Cyclizine
- Doxylamine with pyridoxine
- Metoclopramide
- Prochlorperazine
- Promethazine hydrochloride + promethazine teoclate
- Ondansetron.
“Zines”
When used in 3rd trimester can cause irritability/jitteriness in newborns
What anti-emetics are limited to 5 days use?
Metoclopramide
Ondansetron
What anti-emetic is limited to 7 days use?
Domperidone
What are the risk factors for PONV?
- Anaesthetic used
- Type + duration of surgery
- Females
- Non smokers
- Previous history
- Motion sickness
- Opioid use
Antiemetic prevention (PONV)
- 5-HT3 receptor antagonists
- Droperidol
- Dexamethasone
- Phenothiazine antipyschotics (e.g. prochlorperazine)
- Antihistamine e.g. cyclizine
High risk of PONV
Combination of 2 or more antiemetics from differing drug classes
