1. Nausea and vomiting

2. Vagal/splanchnic afferents
Cerebral cortex
Vestibular nuclei
CTZ
GABA 5HT
ACh H1
5HT3 D2
Gut wall
Vagal/splanchnic afferents
Gastric atony
Retroperistalsis
Thoracic and abdominal muscle contractions
Vomiting centre
5HT3
ACh H1 5HT2

3. Movement/vertigo
Vestibular nuclei
CTZ
Gastric atony
Retroperistalsis
Thoracic and abdominal muscle contractions
Vomiting centre

4. Hyponatraemia
Fear/anxiety
Raised ICP
Vestibular nuclei
CTZ
Gastric atony
Retroperistalsis
Thoracic and abdominal muscle contractions
Vomiting centre

5. HypercalcaemiaUraemia Morphine Cytotoxic chemotherapy
Vestibular nuclei
CTZ
Gastric atony
Retroperistalsis
Thoracic and abdominal muscle contractions
Vomiting centre

6. Intestinal Distension
Vestibular nuclei
CTZ
Intestinal Distension
Cytotoxic chemotherapy
Vomiting centre
Gastric atony
Retroperistalsis
Thoracic and abdominal muscle contractions
Abdominal RXT
Gastric irritants

7. Case studies
Pick the most appropriate antiemetic in each case

8. Management Treat reversible causes
Remember unrelated causes e.g gastroenteritis
Choose the most appropriate antiemetic for the cause
Prescribe the same antiemetic regularly and prn
If oral absorption in doubt, use sc route
Remember non-drug treatments
Consider dexamethasone
REVIEW

9. Common anti-emetics Prokinetic
for gastric stasis, functional bowel obstruction
Metoclopramide 10mg tds
or 30-60mg/24hr CSCI
Acting on CTZ trigger zone
for chemical causes of vomiting eg morphine, renal failure
Haloperidol 1.5-3mg stat/nocte
or 2.5-5mg sc stat and mg/24hr CSCI

10. Common anti-emetics Antispasmodic and antisecretory
if bowel colic and/or need to reduce GI secretions
Buscopan 20mg stat
60 – 120mg/24hr CSCI
Acting in the Vomiting Centre
for raised ICP, motion sickness or mechanical bowel obstruction
Cyclizine 50mg tds
150mg/24hr CSCI
Broad-spectrum
for mechanical obstruction, or if others fail
Levomepromazine mg nocte

11. Nausea and Vomiting Cause Clinical Picture Rx
Metabolic (drugs, uraemia, hypercalcaemia)
Persistent nausea
Haloperidol
Levomepromazine
Gastric stasis
Occ. nausea relieved by vomiting
Metoclopramide
Domperidone
Bowel obstruction
(abdo. ca./autonomic neuropathy)
Nausea relieved by vomiting ± colic ± faecal vomit
Buscopan/ levomepromazine
Cyclizine
↑ ICP, brainstem disease
Headache
Cyclizine ± dex.
Vestibular disease
Movement related
1)Cyclizine
2) Levomepromazine
Bentley A, Boyd K. Palliative Medicine 2001;15:

12. Summary
Try to establish the cause and choose an appropriate antiemetic, rather than picking your favourite
Avoid combinations that may antagonise each other
Choose an appropriate route