GI Pharmacology Flashcards
Risk factors of gastric and duodenal ulcers
- Helicobacter pylori
- NSAIDs
- early gastric emptying
- smoking + alcohol delay healing
Common causes of gastric + duodenal ulcers
Helicobacter pylori (most common)
NSAIDs
Example of alginates + antacids
Gaviscon
What class of drug is gaviscon?
Alginate + antacid
What are the uses of gaviscon?
GORD
What is the mechanism of action of gaviscon?
- antacid: buffers stomach acid
- alginic acid: increase stomach content viscosity + reduce reflux
What is gaviscon composed of?
- alginic acid: sodium alginate
- antacid: aluminium hydroxide/magnesium carbonate
What are adverse drug reactions of gaviscon?
Magnesium salts can cause diarrhoea
Aluminium salts can cause constipation
Why is the antacid part of gaviscon often composed of both aluminium hydroxide AND magnesium carbonate?
- magnesium salts can cause diarrhoea
- aluminium salts can cause constipation
- attempt to balance out the adverse drug reactions
. - magnesium hydroxide gastric pH higher + faster than aluminium hydroxide (AlHO has longer duration)
What are contradictions of gaviscon?
- renal failure in Na+ + K+ containing preparations
- diabetes mellitus in high sucrose conc preparations
What are important drug drug interactions of gaviscon?
- Can reduce absorption of drugs so doses should be separated
- Increased urine alkalinity can increases aspirin excretion
Examples of proton pump inhibitors
Omeprazole
Lansoprazole
What are the uses of PPIs?
Helicobacter pylori eradication
Peptic ulcers + relapse prevention
Co prescribed within NSAIDs
What is the mechanism of action of PPI?s
Irreversibly inhibition H+/K+ ATPase in parietal cells > reduction in acid secretion
What are adverse drug reactions of PPIs?
- abdominal pain
- diarrhoea
- constipation
- headache
- dizziness
- drowsiness
- can mask symptoms of gastro-oesophageal cancer