Anti-ulcer agents Flashcards
What are the 2 causes of gastric ulcers?
Drugs and disease
What drugs can cause gastric ulcers?
NSAIDs, steroids
Which diseases can causes gastric ulcers?
- Shock
- Hypotension
- Trauma
- Bile reflux
- Metabolic disease
How do ulcers form?
When normal protective barrier of gut breaks down allowing acid to reach and damage epithelial cells
What are the 3 main pathways that stimulate acid secretion in parietal cells?
- Stimulation of muscarinic receptors
- Stimulation of gastrin receptor
- Stimulation of histamine receptors
What is the function of prostaglandin?
Inhibits proton pump and stimulates blood flow to gut muscosa. This dilutes effect of acid and stimulates mucous production protecting mucosa.
What are the 5 therapeutic options used to treat ulcers?
- Antacids
- H2- receptor antagonists
- Proton pump inhibitors
- PGE2 analogues
- Sucralfate
Describe the mechanism of action of antacids
- Chemically neutralise gastric HCl
- Inhibits pepsin secretion
What are the main uses of antacids?
Non-specific therapy
What are the side effects associated with antacids?
- Rebound acid secretion –> body detects pH is too high, stimulated to secrete acid to bring down
- Constipation (Al)
- Diarrhoea (Mg)
- Impair absorption of other drugs
Describe the mechanism of action of H2 receptor antagonists
Competitive antagonism of H2 receptors in parietal cells
Describe the pharmacokinetics of H2 receptor antagonists
- Oral administration
- Hepatic metabolism
- Renal excretion
What are H2 receptor antagonists mainly used to treat?
Gastritis, gastric ulcers, oesophagitis
Describe the mechanism of action of proton pump inhibitors
Inhibits H+-K+ ATPase pump on luminal membrane of parietal cells. Binds irreversibly.
Describe the pharmacokinetics of proton pump inhibitors
- Oral administration
- Accumulates in parietal cells
- Hepatic metabolism
What are the main uses of proton pump inhibitors?
Gastritis, gastric ulcers, oesophagitis, prevention/treatment of ulcers caused by NSAIDs.
Are there any side effects associated with proton pump inhibitors?
Minimal
Describe the mechanism of action of PGE2 analogues
Agonist at PG receptor –> decreases gastric acid secretion, increases mucosal blood flow and mucous secretion.
Describe the pharmacokinetics of PGE2 analogues
Oral administration.
What are the main uses of PGE2 analogues?
Preventioin/treatment of ulcers caused by NSAIDs.
Are there any side effects associated with PGE2 analogues?
- Diarrhoea.
- Can have -ve impact on repro tract so don’t give to pregnant animals
Describe the mechanism of action of sucralfate
- Polymerises to a viscous gel at pH<4
- Binds to protein in ulcerated tissue
What are the main uses of sucralfate?
Gastric and duodenal ulcers
Are there any side effects associated with sucralfate?
Constipation, slow gut transit time.
