Drugs to treat disorders of acid secretion

Question 1

What drug classes can be used to treat disorders of acid secretion?

Answer 1

Antacids and alginates
Histamine H2 receptor antagonists
Proton Pump Inhibitors

Question 2

What is an antacid?

Answer 2

Any substance (generally a base) which counteracts stomach acidity. 
Act by buffering gastric acid, raising pH

Question 3

Name 2 examples of antacids

Answer 3

Aluminium Hydroxide + Magnesium Hydroxide (Maalox)

Calcium Carbonate + Magnesium Carbonate (Rennie’s)

Question 4

What is an alginate?

Answer 4

Anionic polysaccharides that form a viscous gel upon binding water.
Increase viscosity of stomach contents to protect oesophagus from acid reflux.

Question 5

Name an example of an alginate?

Answer 5

Sodium alginate, sodium bicarbonate, calcium carbonate (Gaviscon)

Question 6

What is the MoA of Histamine H2-receptor antagonists?

Answer 6

Competitively inhibit histamine receptors on parietal cells

Question 7

Name 2 examples of Histamine H2-receptor antagonists

Answer 7

Cimetidine (Tagamet)

Ranitidine (Zantac)

Question 8

What is the MoA of PPIs?

Answer 8

Irreversibly inhibit the H+/K+ ATPase pump (terminal step in acid secretory pathway)

Question 9

Name 2 examples of PPIs

Answer 9

Omeprazole

Lansoprazole

Question 10

What conditions would require drug treatment of acid secretion?

Answer 10

Reflux oesophagitis 
Peptic ulcers (can be caused by NSAID use or H. Pylori infection, amongst others)

Question 11

What is reflux oesophagitis?

Answer 11

Inflammation of the lower oesophagus produced by persistent episodes of reflux (GORD)

Question 12

What are the symptoms of reflux oesophagitis?

Answer 12

Heartburn
Regurgitation
Haematemesis (vomiting blood)

Question 13

What are potential complications of reflux oesophagitis?

Answer 13

Oesophageal ulceration
Peptic stricture
Barrett’s oesophagus

Question 14

What is the pharmacological management of reflux oesophagitis?

Answer 14

Step 1: Antacids + Alginates (OTC)
Step 2: H2-receptor antagonists (OTC, if above fails)
Step 3: PPIs (prescribed for more severe cases)

Question 15

How can NSAIDs cause peptic ulcers?

Answer 15

Inhibit prostaglandin synthesis and impair renewal of the gastric mucosal barrier

[Prostaglandins increase mucus and bicarbonate production and inhibit acid secretion]

Question 16

What precautions can be taken to reduce risk of GI-adverse effects in patients taking NSAIDs?

Answer 16

Alternative drug?
Low dose
Short duration 
Frequent review 
Co-prescription of PPI in high risk patients

Question 17

What is H. Pylori?

Answer 17

Spiral-shaped, gram-negative bacterium that causes damage to stomach and duodenal tissue

Question 18

How does H.Pylori cause peptic ulcers?

Answer 18

Secretes Urease - breaks down Urea into CO2 and NH3
NH3 neutralises gastric acid
H.Pylori penetrates mucus barrier
NH3, bacterial products and acid damage epithelial cells

Question 19

How can H.Pylori be treated?

Answer 19

Long term combination of antibiotics and a PPI

Question 20

What is hypochlorydria?

Answer 20

Absence/ deficiency of hydrochloric acid in gastric juice

Question 21

What are the consequences of hypochlorydria?

Answer 21

1. Impaired ability to absorb certain nutrients (e.g. iron and B vitamins)
2. Increased vulnerability to bacterial infections in the GI tract

Question 22

What is Zollinger-Ellison Syndrome?

Answer 22

Presence of a gastrin-secreting tumour or hyperplasia of the islet cells of the pancreas causing overproduction of stomach acid and recurrent peptic ulcers