Anti-Emetics Flashcards
4 main classes of anti-emetics?
5-HT receptor antagonists
Histamine receptor antagonists
Muscarinic receptor antagonists
Dopamine receptor antagonists
How does cisplatin result in 5-HT release
Toxic to enterochromaffin cells, causes them to apoptose, releases free radicals as well as 5-HT
Enterochromaffin cells apoptosis results in release of what
free radicals as well as 5-HT
Where do the emetic nerve fibres from the stomach go to in the brain
nucleus tractus solitarius, vomiting centre, and CTZ
Where is the vomiting centre in the brain
Medulla oblongata
What part of the brain has emetic fibres to the stomach
The vomiting centre in the medulla oblongata
Vomiting centre AKA
Area postrema
Area postrema AKA
Vomiting centre
How is the positioning of the chemoreceptor trigger zone useful to its function?
Outside BBB so can detect shit in blood
How does the stomach induce vomiting
Serotonin stimulates 5-HT receptors, which have nerves projecting up to the NTS, VC and CTZ, when then have fibres to the VC, which then triggers emesis
Treatment for stomach induced emesis?
Ondansteron - 5HT antagonist
Example of 5HT antagonist/
Ondansteron
Ondansteron iss an example of?
5HT antagonist
Main use of a 5HT receptor antagonist?
Chemotherapy induced nausea and vomiting
Main use of a histamine H1 receptor antagonist?
Motion sickness
Main use of a muscarinic receptor antagonist?
Motion sickness
Main use of a dopamine receptor antagonist?
Gastroperesis induced N&V
Treatment for Chemotherapy induced nausea and vomiting
5HT receptor antagonist
Treatment for motion sickness?
muscarinic receptor antagonist
Treatment for Gastroperesis induced N&V
dopamine receptor antagonist
Role of the nucleus tractus solitarius?
Innervates the vomiting centre
Role of the CTZ?
communicates with the VC
Mechanistic triggers of emesis?
Cytotoxic drugs, motion sickness, GI problems
Why do we get motion sickness?
Visual/neural mismatch
What receptors connect the labyrinth and vestibular systems
Muscaronic M1-5
What receptors connect the vestibular systems and VC
Muscarinic M1-5
What receptors connect the hypothalamus and CTZ
Histamine H1-receptor
Where does promethazine act
H1 receptor antagonist, blocks signals from hypothalamus to CTZ
Where does hyoscine act
Muscarinic receptor for neurons from labyrinth to vestibular system, and vestibular system to VC
What is promethazine
H1 receptor antagonist
What is hyoscine
Muscarinic receptor antagonist
How does gastroparesis trigger emesis (2)
Reduced stomach contraction activates 5HT receptors in stomach which sends signals directly to VC and releases dopamine to stimulate its D2 receptors
There are also fibres to the CTZ
What is the treatment for gastroparesis induced N&V
Metoclopramide - D2 receptor antagonist
And 5HT receptor antagonist to inhibit activation of CTZ
Effects of metoclopramide (2)
Prokinetic - stimulates gastric emptying
Inhibits D2 receptors in VC
Slight 5HT receptor antagonist to inhibit activation of CTZ
Example of a D2 receptor antagonist
Metaclopramide
Side effects of 5HT receptor antagonism (2)
- Headaches
- Constipation
Side effects of histamine H1 receptor antagonism
- Drowsiness
Side effects of dopamine D2 receptor antagonism
- Extrapyramidal side-effects
Side effects associated with MUSCARINIC RECEPTOR ANTAGONISM:
- Drowsiness
- Dry mouth
- Constipation
