GI pharmacology - Full summary

Question 1

What are some examples of Histamine H2 antagonists?

Answer 1

Ranitidine
Cimetidine
Famotidine
Nizatidine

Question 2

How does histamine affect HCl production?

Answer 2

Histamine binds to H2 receptors, which activates adenylyl cyclase
This converts AMP to cAMP
cAMP increases production of proton pumps, which increases secretion of HCl

Question 3

How do anti (H2) histamines work?

Answer 3

They block H2 receptors on parietal cells and thus prevent the action histamine, as it increases HCl production
Anti (H2) histamines therefore decrease HCl production

Question 4

What conditions are anti-histamines (H2) indicated in?

Answer 4

Benign gastric acid ulceration
NSAID associated ulceration

Question 5

How can tolerance form against anti-histamines (H2)?

Answer 5

After 4 weeks, down regulation of the histamine pathway can cause up regulation of the acetylcholine and gastrin pathways, therefore increasing HCl secretion

Question 6

What are some examples of muscarinic (M3) antagonists used in control of stomach acid production?

Answer 6

Solifenacin
Darifenacin

Question 7

How do antacids work?

Answer 7

They work as a buffering system
They contain salt based compounds such as NaHCO3 and CaCO3, which dissociate and buffer the H+ ions of the HCl, therefore decreasing the acidity of the stomach acid

Question 8

What are some gastrointestinal side effects of NSAIDs?

Answer 8

Gastric bleeding
Ulceration
Abdominal discomfort

Question 9

How can NSAIDs cause increased stomach acid production?

Answer 9

NSAIDs prevent the production of prostaglandins, which increases histamine levels and decreases mucosal protection of the stomach lining

Question 10

What is misoprostol?

Answer 10

This is a chemical analogue of prostaglandin E1

Question 11

In what conditions is misoprostol indicated?

Answer 11

prophylaxis of NSAID induced ulcers

Question 12

What are some side effects of misoprostol?

Answer 12

Abdominal pain
Diarrhoea
Induces uterine contractions and labour

Question 13

What are some examples of proton pump inhibitors?

Answer 13

Lansoprazole
Omeprazole
Pantoprazole
Esomeprazole

Question 14

How do proton pump inhibitors work?

Answer 14

They irreversibly antagonise the H+/H+ ATPase which allows for the secretion of Cl- ions into the gastrointestinal lumen

Question 15

What is a possible side effect of PPI use?

Answer 15

Increased susceptibility to GI tract infection

Question 16

In what conditions are PPIs indicated in?

Answer 16

Benign peptic ulceration
NSAID associated ulceration
Gastro-oesophageal reflux disease
Zollinger-Ellison syndrome

Question 17

How does Helicobacter pylori cause peptic ulceration?

Answer 17

It coalesces in the mucus lining, destroying mucus producing cells, therefore depleting bicarbonate production and allowing HCl to damage the stomach lining, leading to peptic ulceration

Question 18

What is the treatment regime for H.pylori infection?

Answer 18

Proton pump inhibitors
Clarythromicin
Metronidazole (Or amoxicillin)