Stomach

Question 1

What type of drug can be used to prevent long term gastric damage caused by NSAIDs?
Give an example
How does it work?

Answer 1

A stable PGE1 analogue
E.g. Misoprostol
Inhibits basal and food-stimulated gastric acid formation
Also maintains secretion and mucus and bicarbonate

Question 2

How does H.pylori cause gastric ulcers?

Answer 2

It secretes agents which cause persistent inflammation that weakens the mucosal barrier
This damages the mucosal cell layerand leaves the submucosa subject to attack by HCL

Question 3

What are the three aims of drug treatment used to promote ulcer healing?

Answer 3

1. Reducing acid secretion
2. Increasing mucosal resistance
3. Eradicating H.pylori

Question 4

How do proton pump inhibitors work?

Answer 4

E.g. omeprazole
Inhibit the active (i.e. membrane inserted) H+/K+-dependent ATPase (proton-pump) to inhibit acid secretion
They are inactive at a neutral pH, but change conformation in a strongly acidic environment
Timing of dosing is important – drug must be present in plasma at an effective concentration whilst proton pumps are active.

Question 5

How do histamine H2 receptor antagonists work?

E.g.

Answer 5

E.g. Ranitidine, cimetidine
Act as competitive (reversible) antagonists of H2 receptors
Completely block the histamine-mediated component of acid secretion and reduce secretion evoked by gastrin and Ach
Are effective against basal and stimulated gastric acid production
Are effective once/twice daily by oral administration
Unwanted effects (of ranitidine) are rare
Are used in the treatment of peptic ulcer and reflux oesophagitis

Question 6

Give two examples of drugs used to strengthen the mucosa

Answer 6

Sucralfate

Bismuth chealate

Question 7

Varices
What are they?
What are they caused by?
Complications?

Answer 7

Increased pressure in the portal vein causes the development of large, swollen veins (varices) within the esophagus and stomach. The varices are fragile and can rupture easily, resulting in a large amount of blood loss. The most common cause of portal hypertension is cirrhosis of the liver.

Question 8

What are the most common cancers found in the stomach?

Answer 8

Adenocarcinoma - caused by H.pylori and other factors
Lymphoma
GISTs - gastrointestinal stroma tumours

Question 9

In terms of surgery, how is a proximal vs distal tumour treated?

Answer 9

Total gastrectomy for proximal lesions

Patial gastrectomy for distal lesions

Question 10

According to the Rome III criteria, what are the three main groups of dyspepsia?

Answer 10

1. Epigastric pain or burning (epigastric pain syndrome)
2. Postprandial fullness (postprandial distress syndrome)
3. Early satiety (postprandial distress syndrome)

Question 11

What are some common risk factors for gastric and duodenal ulcer formation?

Answer 11

H.pylori; drugs - e,g NSAIDs, steroids; increased gastric acid secretion; smoking, slow gastric emptying

Question 12

What is the main difference in symptoms between gastric ulcers and duodenal ulcers?

Answer 12

Duodenal ulcers cause pain before meals (or at night), and pain is relieved by eating or drinking milk
Gastric ulcers cause pain on eating, and are relieved by antacids

Question 13

What is functional dyspepsia?

Answer 13

Presence of one of the following:
- Bothersome postprandial fullness
- Early satiation
- Epigastric pain
- Epigastric burning
And no evidence of anystructural disease

Question 14

What is the most accurate non-invase test for H.pylori?

Answer 14

C13 breath test

Question 15

What is the current treatment for H.pylori?

Answer 15

Either:

1. Full dose PPI + amoxicillin + clarithromycin
2. Full dose PPI + metronidiazole + clarithromycin

Question 16

What is the pathogenesis from H.pylori infection to gastric carcinoma?

Answer 16

H.pylori infection –> chronic gastritis –> intestinal metaplasia/atrophy –> dysplasia –> carcinoma

Question 17

5-HT3 receptor antagonists - “Setrons”
E.g.
What are they used for?
How do they work?

Answer 17

Ondanstron, palonosetron
Used to suppress chemotherapy and radiation induced emesis and post operative nausea and vomiting
5-HT activates these receptors, which are connected to the vomiting center in the brain by vagal afferents, something to do with Na influx

Question 18

Muscarinic acetyl choline receptor antagonists
E.g. 
What are they used for?
How do they work?
Side effects?

Answer 18

Hyosine, scopolamine
Used for prophylaxis of motion sickness
Probably block muscarinic acetylcholine receptors at multiple sites, inhibiting GI movements
Numerous unwanted effects including blurred vision, urinary retention, dry mouth

Question 19

Histamine H1 receptor antagonists
E.g.
What are they used for?
Side effects

Answer 19

E.g. Cyclizine, cinnarizine
Used for prophylaxis and treatment of motion sickness, acute labyrinthitis, and N&V caused by irritants
Causes drowsiness and sedation

Question 20

Dopamine receptor antagonists
E.g.
What are they used for?

Answer 20

E.g. domperidone, metoclopramide

Used for drug induced vomiting and vomiting in GI disorders