Anti-Ulcer Drugs Flashcards
What are the two types of peptic ulcer?
Gastric ulcer
Duodenal ulcer
Describe how gastric ulcers and duodenal ulcers can be distinguished based on their symptoms.
Gastric ulcer – pain at meal times when gastric acid is secreted
Duodenal ulcer – pain relieved by a meal as the pyloric acid closes –pain -3 hours after a meal
Which type of peptic ulcer is more common?
Duodenal (4:1)
What are the protective factors that protect the stomach lining from damage?
Mucous lining the stomach
Bicarbonate produced by cells in the stomach
Prostaglandins facilitate a good blood flow in the stomach, increasemucous and bicarbonate production and inhibit acid secretion
Which cells produce stomach acid?
Parietal cells
Which cells produce pepsinogens?
Gastric chief cells
State some factors that could contribute to the pathogenesis of ulcers.
Increase in acid production Decrease in bicarbonate production Decreased thickness of mucosal layer Increase in pepsin Decreased mucosal blood flow Increase in H. pylori
What is the aim of antibiotics treatment with regards to ulcers?
90% eradication of H. pylori within 7-14 days
What is a simple way of testing for the presence of helicobacter in a subject?
Give a urate mixture that contains a distinctive isotope of carbon
H. pylori has enzymes that can break down the urate mixture and liberate the carbon isotope
This carbon isotope is then incorporated into carbon dioxide and is breathed out – this can then be detected to confirm high levels of H. pylori
What treatments can be put together to form the best practice ‘Triple Therapy’?
Antibiotics
Drugs that reduce gastric acid secretion
Drugs that promote healing
Where are parietal cells found in the stomach?
Fundus
Which cells in the stomach produce histamine?
H cells
Explain how the parasympathetic nervous system affects gastric acid production.
The parasympathetic nervous, via the vagus nerve, stimulates histamine production by H cells
Histamine then stimulates an increase in acid production by parietal cells
Which cells in the stomach produce gastrin and where are these cells found?
G cells
Located in the antrum
What triggers gastrin release from G cells?
The breakdown of food in the stomach and the liberation of amino acids stimulate gastrin release
What are the effects of gastrin?
They trigger the release of histamine from H cells
They also directly trigger acid production by the parietal cells
What do D cells release?
Somatostatin
What are the effects of somatostatin?
It is inhibitory – it decreases the release of histamine and gastrin
What type of ion transporter is the proton pump found in parietal cells?
H+/K+ ATPase
Which cells produce bicarbonate?
Superficial epithelial cells
Give an example of a proton pump inhibitor.
Omeprazole
What is the mechanism of action of PPIs?
Irreversible inhibitors of H+/K+ ATPase
What are the effects of PPIs?
Inhibits basal and stimulated gastric acid secretion from the parietal cells by >90%
What features of PPIs limits its action on other proton pumpsaround the body?
Inactive at neutral pH
It is a WEAK BASE so it accumulates in the cannaliculi of the parietal cells – this concentrates its actions in the cannaliculi
