Drugs Affecting Acid Secretion Flashcards Preview

ESA 5 - Pharmacology > Drugs Affecting Acid Secretion > Flashcards

Flashcards in Drugs Affecting Acid Secretion Deck (43)
Loading flashcards...
1
Q

Why is anti-reflux surgery rarely used nowadays?

A

Because drugs have taken over their function

2
Q

What happens in anti-reflux surgery?

A

The gastric fundus gets wrapped around the LOS and supports it

3
Q

What defensive factors does the gastric mucosa have?

A
  • Epithelial integrity
  • Cell replication and restitution
  • Mucous membrane barrier
  • Vascular supply
4
Q

What factors can damage the gastric mucosa?

A
  • Acid
  • Helicobacter pylori
5
Q

How deep is the gastric mucous barrier?

A

2-3mm

6
Q

How much does the pH change in the gastric mucosa?

A

From pH 2 to pH 7

7
Q

Why do cuts to gastric mucosa heal very quickly?

A

Because they have extra cells at the bottom of pits that can quickly migrate to the surface if needed

8
Q

What drug targets are found in the parietal (oxyntic) cell?

A
  • Stimulatory receptors
  • Proton pumps
9
Q

Where in the parietal cells are the stimulatory receptors found?

A

Those in the baso-lateral membrane

10
Q

What stimulatory receptors are found in the parietal cell?

A
  • Gastrin receptors
  • Histamine receptors
  • ACh receptors
11
Q

What does the proton pump do?

A

Exchanges protons for potassium

12
Q

Blocking which parietal cell stimulatory receptor has the most effect?

A

H2 receptor antagonists

13
Q

How does the parietal cell proton pump work?

A

It uses ATP to provide energy to swap H+ for K+

14
Q

How long does the onset of action of proton pump inhibitors take?

A

2-3 days

15
Q

Why is the onset of action of proton pump inhibitors delayed?

A

Because not all pumps are active all the time

16
Q

What does restoration of acid secretion after giving a proton pump inhibitor require?

A

De novo synthesis, as PPI destroys the pumps in an irreversible process

17
Q

What hormones are involved in the neuro-endocrine regulation of acid secretion?

A
  • Cholecystokinin B
  • Gastrin and gastrin releasing protein
  • Somatostatin
18
Q

What cells are involved in the neuro-endocrine regulation of acid secretion?

A

Enterochromaffine like cells

19
Q

How are PPI prodrugs activated?

A

With acid

20
Q

How do PPIs exert their action on the K/H-ATPases?

A

They bind covalently to cysteines of ATPases

21
Q

Do H2 receptor antagonists have a long or short half life?

A

Short

22
Q

What is the result of the short half life of H2 receptor antagonists?

A
  • Faster onset of action
  • Requires twice a day dosing
23
Q

What % of duodenal ulcers are associated with H pylori?

A

96%

24
Q

What % of gastric ulcers are associated with H pylori?

A

75%

25
Q

What categories of drugs can be used for peptic disorders?

A
  • Antacids
  • Alginates
  • H2 receptor antagonists
  • PPIs
26
Q

Give two examples of antacids

A
  • Rennies
  • Gaviscon
27
Q

How do antacids work?

A

They act as buffers

28
Q

What happens once the buffering effect of antacids is exhausted?

A

You get symptoms

29
Q

Give an example of an alginate

A

Sucralfate

30
Q

What are alginates?

A

Complex molecules that adhere to exposed mucosa, and form a barrier

31
Q

What is good about alginates?

A
  • Can take several times a day to achieve good symptomatic relief
  • Last a bit longer than antacids
32
Q

Why are alginates not used more clinically?

A

Because there is no money in them, and so no one will pay for clinical trials

33
Q

Give four examples of H2 receptor antagonists

A
  • Cimetidine
  • Ranitidine
  • Nizatidine
  • Famotidine
34
Q

What is the clinical advantage of H2 receptor antagonists?

A

They are safe, with minimal side effects

35
Q

What is the problem with the use of cimetidine?

A

It metabolises with P450, so causes side effects, particular gynacomastia

36
Q

Give 5 examples of PPIs

A
  • Omeprazole
  • Lansoprazole
  • Rabeprazole
  • Pantoprazole
  • Esomeprazole
37
Q

What are the principles of GORD treatment?

A
  • Symptom control
  • Healing of oesophagitis
38
Q

What steps are taken in GORD symptom control?

A
  1. Lifestyle changes
  2. Antacids or alginates
  3. H2 receptor antagonists
  4. PPIs
39
Q

How should peptic ulceration be managed?

A
  • Stop NSAIDs if at all possible
  • H2 receptor antagonists and PPI for 6 weeks
  • H pylori eradication
40
Q

How is H pylori eradication achieved?

A
  • 2 antibiotics and full acid blockade with PPI
41
Q

What is the side effect of H pylori eradication treatment?

A

Get bad diarrhoea

42
Q

How long is H pylori eradication treatment?

A

At least 7 days

43
Q

Why is it important to complete H pylori eradication treatment?

A

Because if you get treatment failure the first time, you are at a much greater risk of non-eradication in subsequent attempts