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Pharmacology Of Gi System Notes

Medicine Notes > Gastrointestinal (GI) System Notes

This is an extract of our Pharmacology Of Gi System document, which we sell as part of our Gastrointestinal (GI) System Notes collection written by the top tier of Bristol University students.

The following is a more accessble plain text extract of the PDF sample above, taken from our Gastrointestinal (GI) System Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Lecture 5 Pharmacology of GI system LECTURE 1

* Nausea and vomiting o

? General


*Act centrally to inhibit or prevent emesis Include antagonists of o D2 receptor (chemical trigger zone) o 5-HT receptor (chemical trigger zone) o H1-receptor (NTS) o AChM receptor (vomiting centre)





D2 Dopamine receptor antagonists o Phenothiazines- CHLORPROMAZINE & ACEPROMAZINE
? General

* Good at preventing vomiting agents directly stimulating CTZ

* Sedative action= more useful for motion sickness

* Also antagonises H1 and AChM receptors (dirty)
? Side effects

* Hypotension, platelet dysfunction, ataxia

* Not recommended for pregnant, affects babies (+500mg) o METACLOPRAMIDE
? General

* Blocks 5-HT3 receptors= large part of effect

* Peripheral actions- increased muscle tone in lower oesophageal sphincter (near stomach) to prevent vomiting
? Side effects

* As chlorpromazine, Diarrhoea 5-HT receptor antagonists o ONDANSETRON
? Particularly useful in chemo/radiotherapy
? Side effects: drowsiness & dizziness o NABILONE
? Synthetic cannabinoid (not first choice- addiction)
? Used in cytotoxic-induced vomiting
? Side effect: drowsiness & dizziness 5-HT4 receptor agonists o CISAPRIDE
? General

* Peripherally, increasing gastro-oesophageal sphincter contraction & GI motility

* Withdrawn= long QT-syndrome (death)
? Side effects (high dosage)

* Diarrhoea, abdominal cramp

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