gastrointestinal pharmacology Flashcards
1
Q
clinical indications of gastric problems
A
- H.pylori
- peptic ulceration
- reflux oesophagitis
- gastrin producing tumours (zollinger-Ellison syndrome)
- NSAIDs induced ulceration
2
Q
main receptors in parietal cells
A
- histamine II receptor
- muscarinic III receptor
- cholescystokinin II receptors
3
Q
examples of drugs of proton pump inhibitors (PPIs)
A
- omeprazole
- esomeprazole
- lansoprazole
4
Q
mechanism of action of proton pump inhibitors (PPIs)
A
- irreversibly inhibit the H/K ATPase
- accumulates in canaliculi of parietal cells
- specific inhibition of acid secretion (H2 and M3 antagonism)
- inhibit both basal and stimulated acid secretion
5
Q
pharmacokinetics effects of PPIs
A
- inhibitory effect on acid secretion can increase bioavailability
- single dose can inhibit about 2-3 days
- half life ~ 1 hour
6
Q
unwanted effects of PPIs especially omeprazole
A
- inhibits 2C family of CYP450
- decreased metabolism of warfarin, carbamazepine, phenytoin
- long term increased gastrin production cause gastric neoplasia
- headache
- diarrhoea
- rashes
7
Q
examples of drugs of histamine H2 receptor antagonists
A
- cimetidine
- ranitidine
- famotidine
8
Q
mechanism action of HH2 receptor antagonists
A
- competitively inhibit HH2 receptors
- inhibits histamine, gastrin, and Ach-stimulated acid secretion
- decrease both basal and food-stimulated acid secretion by 70%
- promote healing of gastric and duodenal ulcers
9
Q
unwanted effects of HH2 receptors antagonists
A
- gynaecomastia
- decreased sexual function
- inhibits CYP450
- potentiate action of oral anticoagulant and TCA
10
Q
examples of antacids
A
- magnesium hydroxide/salt
- sodium bicarbonate
- aluminium hydroxide
11
Q
mechanism of action of antacids
A
neutralise acidity (removal of H+ ion)
12
Q
adverse effects of antacids
A
- sodium bicarbonate causes alkalosis and bloating
- Mg hydroxide causes diarrhoea
- Al hydroxide causes constipation
- combination of Mg and Al preserves bowel function
13
Q
mechanism of action of bismuth chelate
A
- combine with regimens to treat H.pylori
- prevent adherence it to the mucosa
- inhibit its bacterial proteolytic enzymes
14
Q
mechanism of action of sucraflate
A
- inhibit action of pepsin
- stimulate secretion of mucus, bicarbonate, prostaglandin
15
Q
misoprolol?
A
- PGE1 analogues
- prevent gastric damage by NSAIDs
- inhibits basal secretion of gastric acid
- increase secretion of mucus and bicarbonate