29. Treatment of gastric and duodenal ulcers

Question 1

How can we test for H. pylori?

Answer 1

Carbon-urea breath test
• Give patient a lot of urea
• H. pylori metabolises urea to nitrogen
• Increased levels of nitrogen - positive

Stool antigen test
• Test for H. pylori antigens

Question 2

What percentage of duodenal and gastric ulcers are a result of H. pylori infection?

Answer 2

• Duodenal - 98-100%

* Gastric - 70-80%

Question 3

Is H. pylori commensal?

Answer 3

Yes, in the majority of people

Question 4

How does H. pylori cause peptic ulcers?

Answer 4

• Dissolves mucus layer using urease, to access epithelia
• This exposes epithelial cells and leaves them more susceptible to the acidic environment
• Epithelial cell death
• H. pylori releases exotoxins - increased inflammatory reaction (antigenic)
• Damage goes down to the interstitial layer
• Ulcer formed
• Acid exposure can also cause gastric metaplasia

• Increased gastric acid formation
- increased gastrin and decreased somatostatin

• Down-regulation of defence factors
- decreased epidermal GF and decreased bicarbonate production

Question 5

Which type of cells are mainly affected by H. pylori?

Answer 5

Parietal cells in the stomach

Question 6

What does urease catalyse?

Answer 6

Urea => ammonium chloride + monochloride

Question 7

What does CagA and VacA refer to?

Answer 7

• Different strains of H. pylori
• CagA are more antigenic
• VacA are more cytotoxic

Question 8

How can peptic ulcers due to H. pylori be treated?

Answer 8

Amoxicillin + clarithromycin/metronidazole
• Antibiotics
• 2 drug combination is very effective
• Stomach can heal itself very well after

Proton pump inhibitor
• Reduces acid production
• Given for 7 days

Question 9

What investigation do we do if there is epigastric pain and a constant burning sensation (not just after meals), and the H. pylori tests are positive? What is the most likely diagnosis?

Answer 9

• Endoscopy

* Complicated peptic ulcer

Question 10

What can bismuth be used for?

Answer 10

Protect mucus layer

Question 11

How long are PPIs given for complicated peptic ulcers?

Answer 11

4-12 WEEKS

Question 12

What antibiotics are given for complicated peptic ulcers?

Answer 12

• Usual 2 drug combination, or even 3
• Consider quinolone/tetracycline
• May be added alongside first line antibiotics

Question 13

Which systems are the main regulators of the parietal cells producing H+?

Answer 13

Cholinergic and histaminergic system in the stomach

Question 14

How does somatostatin and gastrin (released in the stomach fundus) affect parietal activity?

Answer 14

• Somatostatin reduces parietal cell activity

* Gastrin increases parietal cell activity

Question 15

What is the second most common cause of peptic ulcers?

Answer 15

Prolonged NSAID usage

Question 16

What can bismuth be used for?

Answer 16

Protect mucus layer

Question 17

How long are PPIs given for complicated peptic ulcers?

Answer 17

4-12 WEEKS

Question 18

What antibiotics are given for complicated peptic ulcers?

Answer 18

• Usual 2 drug combination, or even 3
• Consider quinolone/tetracycline
• May be added alongside first line antibiotics

Question 19

Which systems are the main regulators of the parietal cells producing H+?

Answer 19

Cholinergic and histaminergic system in the stomach

Question 20

Describe the regulation of gastric acid in the stomach (4 ways)

Answer 20

1) ACh released from vagus/enteric (parasympathetic) neurones acts on muscarinic (M3) receptors
- increased [Ca2+]
- vesicles with H+K+ATPase moves to apical membrane
- more PP => more acid

2) Prostaglandins from released from local cells act on EP3 receptors
- decreased cAMP
- decreased vesicle migration and acid release

3) Histamine released from enterochromaffin-like cells act on H2 receptors
- increased cAMP
- increased vesicle migration and acid release

4) Gastrin released from blood stream acts on cholecystokinin B receptors
- increased [Ca2+]
- increased vesicle migration and acid release

Question 21

How can NSAIDs cause peptic ulcers?

Answer 21

• Can be directly cytotoxic
• Reduce mucus production
• Anti-platelet - increase likelihood of bleeding

Question 22

How can peptic ulcers due to NSAIDs be treated?

Answer 22

• Remove NSAID drugs

* PPI or histamine H2 receptor antagonist (ranitidine)

Question 23

How do H2 receptor antagonists treat peptic ulcers?

Answer 23

• H2 receptor stimulation increases (PP activity and) acid secretion
• Located on parietal cell
• Antagonism decreases acid secretion

Question 24

Are PPIs always prescribed for peptic ulcers, regardless of aetiology?

Answer 24

Yes

Question 25

Describe the regulation of gastric acid in the stomach

Answer 25

1) ACh released from vagus/enteric (parasympathetic) neurones acts on muscarinic (M3) receptors
- increased [Ca2+]
- vesicles with H+K+ATPase moves to apical membrane
- more PP => more acid

2) Prostaglandins from released from local cells act on EP3 receptors
- increased cAMP
- increased vesicle migration to apical surface

3) Histamine released from enterochromaffin-like cells act on H2 receptors
- increased cAMP
- increased vesicle migration to apical surface