Stomach Acid Drugs

Question 1

What are antacids?

Answer 1

AlOH + MgOH (Maalox)
CaCO3 + MgCO3 (Rennie)
Buffer gastric acid, raising pH to more neutral

Question 2

What are alginates?

Answer 2

Anionic polysacchardides that form a viscous gel on binding with water (usually combined with antacids in treatment of reflux oesophagitis)
Increase viscosity of stomach contents to protect mucosa

Question 3

How do H2 receptor antagonists work in gastric acid disorders?

Answer 3

Competitively inhibit Histamine binding at H2 (H2 receptors on parietal cells stimulate HCL production and secretion)
Cimetidine and Ranitidine

Question 4

How do proton pump inhibitors work?

Answer 4

Omeprazole and Lansoprazole
Accumulate in parietal cell canaliculi and become active at acidic pH -> bind irreversibly to H+/K+-ATPase pump to inhibit terminal step in acid secretion

Question 5

What are symptoms and complications of reflux oesophagitis?

Answer 5

Heartburn, regurgitation, haematemesis

Oesophageal ulceration, peptic stricture, barrett’s oesophagus

Question 6

Where are peptic ulcers most likely to occur?

Answer 6

Duodenum rather than stomach

Question 7

How do NSAIDs contribute to gastric acid disorders?

Answer 7

Prostaglandins E2 and I2 stimulate gastric mucous (HCO3- secretion) and inhibit gastric acid production
NSAIDs inhibit prostaglandin formation = impair renewal of gastric mucosal barrier = gastric erosions/ulcers

Question 8

What do you often prescribe with NSAIDs in elderly or those on high doses?

Answer 8

PPI to reduce GI side effects

Question 9

What’s Helicobacter Pylori? How is it eradicated?

Answer 9

Spiral shaped gram negative bacteria which damages stomach and duodenal tissue

Produces and secretes urease -> NH3 + CO2
NH3 damage epithelial cells
= penetrates mucous barrier allowing acid penetration

Treated with antibiotics + PPI