Drugs Affecting Acid Secretion Flashcards
How comes the gastric mucosa does not self digest?
Defensive factors: Epithelial integrity Cell replication and restitution Mucous membrane barrier Vascular supply
Aggressive factors:
Acid
Helicobacter pylori
Drugs
How often do you have to take H2 receptor antagonists?
Short half life - take twice a day
How long does it take PPIs to work properly, why?
Delayed as not all pumps are active all of the time
Max efficacy after 2-3 days
Restauration of acid secretion requires de novo synthesis
How do H2 receptor antagonists work?
They act on the H2 receptors of the parietal cells of the stomach to decrease the production of stomach acid.
This can be used to treat peptic ulcers and GORD.
But, PPIs have been found to be more effective.
How do PPIs work?
They block the gastric proton pump (H+/K+/ATPase) of parietal cells by binding irreversibly. This prevents acid form being made and means it will take a few days to make acid again after being off these drugs.
Give examples of H2 receptor antagonists
Cimetidine, Ranitidine
Give examples of PPIs
Omeprazole, Lansoprazole
How do you treat GORD symptoms?
Using a ‘step up / step down’ approach
```
Lowest
Lifestyle
Antacids / alginates
H2 receptor antagonists
PPIs
(Highest)
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How do you treat peptic ulceration?
Stop NSAIDs
H2 receptor antagonists / PPIs
H. Pylori eradication
How do you eradicate H pylori?
2 antibiotics and full acid blockade with PPIs
How do prostaglandin analogues work?
They protect GI tract from stomach acid by acting on parietal cells on the stomach wall to inhibit acid secretion.
They also increase mucous and bicarbonate production.
How do antacids work?
They protect the GI tract from stomach acid - neutralise it?
Describe the ADRs of PPIs
headache, nausea, diarrhoea, abdominal pain, fatigue and dizziness.
Describe the ADRs of H2 receptor antagonists
Cimetidine - ADRs common all others ADRS are uncommon.
Hypotension, headache, tiredness, dizziness, confusion, diarrhoea, constipation and rash
