Nausea and vomitting Flashcards
What is vomiting?
The forceful evacuation of gastric content through the mouth
What is Emetic reflex?
Contraction of abdominal muscles and diaphragm increasing pressure in stomach
closure of glottis (prevents vomit entering lungs)
Nausea and vomiting are not a symptoms. TRUE OR FALSE?
FALSE - they are not a dignosis they are simply symptoms and the need to find a cause is important
Name the causes of emisis that may require treatment ?
-motion sickness
-drug induced nausea and vomiting
-post -operative vomiting
-intracranial pathology (eg migraine, increased pressure due to inflammation or
haemorrhage)
-emotional causes
-pain
-drugs and radiation eg during cancer ther
What two brainstem areas control emesis?
- Chemo trigger zone (Fenestrated capillaries allow detection of circulating chemicals)
- Vomiting Centre (Nucleus of the Solitary Tract)
What occurs when chemical and neuronal inputs are intregrated?
- Signals from periphery sense “something wrong”
(Gut chemo-, mechano-sensation) - Signals from higher brain regions “contextualise” other inputs
(Sight & smell; balance; emotion)
What occurs during a vomiting reflex?
Co -ordinated motor-pattern
–Retroperistalsis, gastric contraction, abdominal wall contractio
1.Motion sicknes
2.Drug -induced nausea and vomiting
3.Post -operative vomiting
4.Migraine
5.Chemotherapy (CINV)
what are the treatment options for these 5 different causes of emesis?
1.Anti -histamines, anti-muscarinics
2.try minimize gastric irritation with equal spacing of drug; take with food–otherwise –Dopamine antagonists ,
antihistamine
3.Dopamine antagonists (phenothiazines)
– 5HT3 antagonists
4. Phenothiazines
helpful because also speeds gastric emptying and facilitates absorption of
analgesics
5.dexamethasone, 5HT3 antagonist, NK1 antagonists
Provide an example of anti-histamines (H1) drug?
Cinnarizine
Cyclizine
Promethazine
Promethazine may be used in pregnancy (severe morning sickness) TRUE OR FALSE?
TRUE
What do anti-histamines (H1) drugs act on?
they actt on vestibular apparatus, VC and CTZ
What are the indications for antihistamine drugs?
- Travel sickness,
- Vestibular disorders (vertigo)
- Space motion sickness (Promethazine - NASA)
what are the ADRs for anti-histamines?
- Sedation
- Anti-cholinergic effects (dry mouth, blurred vision, constipation, urinary retention)
- Blocks Ca2+ transport so also causes vasodilation
what are the cautions for anti-histamines?
- Significant antimuscarinic activity
- Use with caution in prostatic hypertrophy, urinary retention, susceptibility to angle-closure glaucoma, and
pyloroduodenal obstruction
Give an example of an anti-muscarinic drug/agent?
Hyoscine hydrobromide (previously known as scopolamine)
what are the indications for anti-muscarinic drug/agent?
OTC for motion sickness (both prophylaxis & treatment), GI disorders
What is the pharmacokinetics of anti-muscarinic drug/agent?
for motion sickness can use patch on skin behind ear
what are some ADRs for anti-muscarinic drugs/agents?
- causes less drowsiness than antihistamines but still caution when driving
- can cause typical anticholinergic ADR
What are the ADRs for anti-muscarinic drugs/agents?
- myasthenia gravis, paralytic ileus, pyloric stenosis, toxic megacolon and prostatic enlargement
Dopamine antagonists acts on CTZ so are useful for motion sickness/ vestibular disorders? TRUE OR FALSE?
FASLE
provide examples of Phenothiazines (dopamine antagonists)
Prochlorperazine
perphenazine
trifluoperazine
(less sedating than chlorpromazine)