Nausea & Vomiting Flashcards
Define emesis.
The process of vomiting
- Nausea
- Retching
- Vomiting
Briefly describe the pathophysiology of N+V.
Stimulus triggers response in vestibular centre, GI tract or chemoreceptor trigger zone
Vagal afferents activates CTZ
CTZ then activates the vomiting centre
Vomiting centre triggers response in GI tract
Give examples of causes of N+V.
Pregnancy Abdominal conditions Raised glucose, bilirubin, calcium Inner ear disorder Malignancy Pain Psychogenic Drugs
Where is the vomiting centre found?
Lower medulla of the brain
Name the neurotransmitters involved in N+V at the vestibular centre.
Histamine
ACh
Name the neurotransmitters involved in N+V at the CTZ.
Serotonin
Dopamine
Substance P
Name the neurotransmitters involved in N+V at the vomiting centre.
Histamine
ACh
Substance P
Serotonin
Name the neurotransmitters involved in N+V at the GI tract.
Histamine ACh Substance P Dopamine Serotonin
Name the neurotransmitters involved in N+V at the vagus nerve.
ACh
Dopamine
Serotonin
Name the neurotransmitter involved in N+V at the higher cortical centres.
Histamine
Describe the action of antihistamines in N+V.
Primarily inhibit histamine in vestibular centre and GIT so do not stimulate CTZ
When are antihistamines useful in N+V.
Motion sickness
Irritants in the stomach
What are the cautions of cinnarizine?
Epilepsy
Parkinson’s
Glaucoma
What are the uses of cinnarizine?
Motion sickness
Vestibular disorders
What are the uses of promethazine?
Motion sickness
Vestibular disorders
Last line in morning sickness
What are the cautions of promethazine?
Epilepsy
Glaucoma
Describe the action of anticholinergics in N+V.
Inhibit ACh primarly present in vestibular centre and GI tract so do not stimulate CTZ
What are the uses of hyoscine?
Motion sickness
What are the cautions of hyoscine?
Cardiac conditions including MI
What are the contraindications of hyoscine?
Bowel obstruction
UC
What are the uses of cyclizine?
For N+V with known cause
What are the cautions of cyclizine?
Epilepsy
Glaucoma
Describe the action of 5-HT3 antagonists in N+V.
Inhibit serotonin in CTZ and GI tract
Give examples of 5-HT3 antagonists.
Ondansetron
Palonosetron
Granisetron
What are the uses of 5-HT3 antagonists?
Chemotherapy, post-op and radiotherapy N+V
How should ondansetron be given in patients over 65?
Via infusion lasting over 15 minutes
What is the major side effect of ondansetron?
QT prolongation
Describe the action of D2 antagonists in N+V.
Inhibit dopamine in CTZ
Give examples of D2 antagonists.
Metoclopramide
Domperidone
Haloperidol
Describe the use of metoclopramide in N+V,
Given orally or IV
Stimulates gut motility
Can cause EPSEs as crosses BBB
What are the contraindications of metoclopramide?
Parkinson’s
What is the MHRA alert for domperidone?
Cardiac toxicity risk
When is haloperidol used in N+V?
Unresponsive/treatment resistant
What is the major side effect of haloperidol?
QT prolongation
Describe the action of NK1 antagonists in N+V.
Inhibit substance P in CTZ
What is the main benefit of NK1 antagonists?
Show efficacy up to 120 hours after single dose
Give examples of NK1 antagonists.
Aprepitant
Fosapreitant
Netupitant
Rolapitant
What is nabilone?
Cannabinoid that acts on CTZ via opioid receptors used last line in N+V
Describe the use of steroids in N+V. Give an example.
Dexamethasone
Used at supra physiological doses
Describe the use of levomepromazine.
Useful in N+V due to wide action however unlicensed
Used in special cases
Name 5 drugs that can be used for N+V in pregnancy.
Metoclopramide Prochlorperazine Cyclizine Promethazine Ondansetron- hyperemesis gravidarum
What are the 4 main risk factors for post-op N+V?
Female
Non-smoker
Previous history of PONV
Peri-op opioid analgesia
What are the 5 types of chemotherapy induced N+V?
Acute Delayed Breakthrough Refractory Anticipatory
What are the risk factors for chemotherapy induced N+V?
Female Age <30 Pre-exisiting N+V Poor control with prior treatment History of N+V Anxiety
What are the protective factors for chemotherapy induced N+V?
History of high alcohol intake
Substance misuse
Smoking
What is given for anticipatory CINV?
Lorazepam
What is commonly given pre-chemo when there is a high risk of N+V?
5-HT3 antagonist
Dexomethasone
NK1 antagonist
What two anti-emetics are used most commonly in a syringe driver?
Cyclizine
Levomepromazine is less irritant and more sedating
What anti-emetics may be used in migraine?
Phenothiazine and antihistamine antiemetics
Buccal prochlorperazine can be bought over the counter
Metoclopramide/domperidone cautioned due to side effects
