GI Pharmacology Flashcards
What is fundoplication surgery?
It is a surgical procedure used, when medical management has failed, for GORD, Barrett’s oesophagus and a hiatus hernia. It involves wrapping the upper part of the stomach around the distal portion of the oesophagus.
What receptors are expressed on the baso-lateral membrane of the parietal cell?
ACh (from Vagus nerve)
Histamine (from ECL Cells)
Gastrin (from G cells).
Give an example of a H2 receptor agonist. State how often it needs to be dosed.
Ranitidine.
Twice daily dosing required.
Describe the changes that occur in a parietal cell as it goes from its resting to active state.
At rest, the proton pumps (which exchange H+ for K+) are not present on the membrane of the cell but are within the cytoplasm on ‘tubulovesicles’. Upon activation, these are inserted into the membrane along canaliculi.
In which state can PPI’s block parietal cells?
Active state only. They need to be on the membrane for the drug treatment to work. Therefore, they take about two hours to start working.
After a course is started, at what point does the activity of the PPI’s peak?
About 2-3 days. It is delayed as not all of the pumps are active all of the time and pumps on the membrane are replenished by unblocked resting pumps from the tubulovesicles in the cytoplasm.
What do PPI’s do to the level of neuro-endocrine inputs to the parietal cells?
As they take part in a feedback look levels of stimulation, particularly of gastrin, rise.
H. Pylori is strongly associated with peptic ulcer disease. Which type of ulcer is most strongly associated with H pylori.
Duodenal ulcers. 96% associated with H. pylori compared to only (!) 75% of gastric ulcers.
Name a notable side effect of PPI’s.
They can cause diarrhoea.
Name one infection to which PPI’s are linked.
They are linked to C. difficile as the absence of acid disables the sterilising influence the stomach has on food.
Name two indications for PPI’s for life.
- Peptic stricture formation.
- Barrett’s Oesophagus
Give a regime that could be used for the eradication of H. pylori.
1x PPI e.g. Omeprazole/ Lansoprazole
2x Abx. Typically amoxicillin + clarithromycin / metronidazole.
