Drugs to Treat Disorders of Acid Secretion

Question 1

What are the 3 main classes of drugs used to treat disorders of acid secretion?

Answer 1

1. Antacids and alginates
2. Histamine H2-receptor antagonists
3. Proton pump inhibitors

Question 2

What is an antacid in terms of medication to treat disorders of acid secretion?

Answer 2

Any substance, generally a base, which counteracts stomach acidity.

Question 3

What effect do antacids have on Pepsin? Why is this?

Answer 3

Antacids inhibit Pepsin activity, because Pepsin is activated by exposure to a low pH, but antacids raise the gastric pH by buffering gastric acid.

Question 4

List 2 brands of antacids and their active ingredients.

Answer 4

1. Rennie - Calcium carbonate and magnesium carbonate.

2. Maalox - Aluminium hydroxide and magnesium hydroxide.

Question 5

Magnesium salts used in antacids can also cause which other side effect?

Answer 5

Diarrhoea.

Question 6

Aluminium salts used in antacids can also cause which other side effect?

Answer 6

Constipation.

Question 7

What are alginates?

Answer 7

Anionic polysaccharides that form a viscous gel upon binding with water.

Question 8

When combined with antacids, alginates are particularly good at preventing which common gastric complaint?

Answer 8

Reflux oesophagitis/ acid reflux/ GORD.

Question 9

What is the drug class of Rennie and Maalox?

Answer 9

Antacids.

Question 10

What is the drug class of Gaviscon?

Answer 10

Antacid + alginate.

Question 11

What are the active ingredients in Gaviscon?

Answer 11

Sodium alginate, sodium bicarbonate, calcium carbonate.

Question 12

What is the MOA of histamine H2-receptor antagonists?

Answer 12

Competitively inhibit histamine actions at H2-receptors.

Question 13

What is the name of the histamine receptor on Parietal cells of the stomach?

Answer 13

H2 receptors.

Question 14

Name a key H2-receptor antagonist that replaced Ranitidine.

Answer 14

Famotidine.

Question 15

Is the inhibition of proton pumps by Omeprazole and Lansoprazole reversible or irreversible?

Answer 15

Irreversible.

Question 16

What happens to the activity of Omeprazole and Lansoprazole at a neutral pH?

Answer 16

They become inactive.

Question 17

Why do Omeprazole and Lansoprazole accumulate in the secretory canaliculi of parietal cells?

Answer 17

They are weak bases which are activated in an acidic environment.

Question 18

What is a prodrug?

Answer 18

A biologically inactive compound which can be metabolised in the body to produce a drug.

Question 19

How do Omeprazole and Lansoprazole enter the parietal cells?

Answer 19

From the circulation via the basolateral membrane.

Question 20

What is GORD?

Answer 20

When the liquid content of the stomach regurgitates into the oesophagus.

Question 21

What is reflux oesophagitis?

Answer 21

Inflammation of the lower oesophagus produced by persistent episodes of reflux.

Question 22

What are some symptoms of reflux oesophagitis?

Answer 22

Heartburn
Regurgitation of food into the mouth
Haematemesis

Question 23

What is haematemesis?

Answer 23

Vomiting blood.

Question 24

List 3 complications of reflux oesophagitis.

Answer 24

1. Oesophageal ulceration
2. Peptic stricture
3. Barrett’s oesophagus

Question 25

What is a peptic stricture? What can it cause difficulties with?

Answer 25

A narrowing or tightening of the oesophagus that causes swallowing difficulties.

Question 26

What is Barrett's oesophagus?

Answer 26

Barrett's oesophagus is a condition in which tissue that is similar to the lining of your intestine replaces the tissue lining your oesophagus via a process called intestinal metaplasia.

Question 27

List 3 common causes of peptic ulcers.

Answer 27

1. NSAIDs 2. Zollinger-Ellison Syndrome 3. H. Pylori infection

Question 28

NSAIDs impair renewal of the gastric mucosal barrier by interfering with the production of what?

Answer 28

Prostaglandins.

Question 29

What 4 things do prostaglandins E2 and I2 do to support renewal of the gastric mucosal barrier?

Answer 29

1. Stimulating gastric mucus production 2. Stimulating bicarbonate secretion 3. Inhibiting gastric acid production 4. Promoting local healing

Question 30

Which enzyme do NSAIDs inhibit? What does this enzyme do?

Answer 30

Cyclo-oxygenase. It catalyzes the first step in the synthesis of prostaglandins from arachidonic acid.

Question 31

If a patient is taking NSAIDs but is at an increased risk of GI-adverse effects, what should be co-prescribed?

Answer 31

Proton pump inhibitor (omeprazole or lansoprazole).

Question 32

What is Zollinger-Ellison syndrome?

Answer 32

A condition in which a gastrin-secreting tumour or hyperplasia of the islet cells in the pancreas causes overproduction of gastric acid, resulting in recurrent peptic ulcers.

Question 33

What shape is H. Pylori and is it Gram-positive or negative?

Answer 33

Spiral shaped and Gram-negative.

Question 34

What enzyme does H. Pylori release? This breaks down what into what?

Answer 34

Urease, which breaks down urea into CO2 and NH3 (ammonia).

Question 35

How does NH3 affect gastric acid?

Answer 35

It neutralises it.

Question 36

What is the standard treatment of a H. Pylori infection?

Answer 36

Antibiotics and a proton pump inhibitor.

Question 37

What are the medical terms for an absence and a deficiency of hydrochloric acid in the gastric juice?

Answer 37

Achlorhydria/ Hypochlorhydria.

Question 38

What are some consequences of achlorhydria and hypochlorhydria?

Answer 38

1. Impaired ability to digest and absorb certain nutrients. | 2. Increased vulnerability of GI tract to bacterial infection.