peptic ulcer diseases Flashcards
what are the 3 classes of drugs that reduce gastric acidity
antacids
H2 receptor antagonists (H2 blockers)
PPI - proton pump inhibitors
what are 3 classes of drugs that are mucosal protective agents
sucralfate
misoprostol
bismuth compounds
what is the triple therapy for H pylori eradication
clarithromycin
amoxicillin
PPI
what are factors that contribute to peptic ulcers
H pylori
NSAIDS
acid
smoking
what is the rate of neutralisation for the 4 different antacids? which form of antacids dissolve better - liquid or tablet?
NaHCO3 > CaCO3 > Mg(OH)2 > Al(OH)3
liquid antacids dissolves better than tablet
why is simethicone found on antacids?
anti-foaming agent
- helps to ease release of gas within Gi tract via burping or flatulence
what are the adverse effects associated with antacids with Na and Ca?
Na: fluid retention, hypertension, caution in HF
Ca: hypercalcemia, rebound acid secretion
both of which can lead to metabolic alkalosis and milk-alkali syndrome
what are the adverse effects associated with antacids with carbonate compounds?
co2 gas formation - gastric distention, belching and flatulence
what are the adverse effects associated with antacids with Mg and Al?
Mg - osmotic diarrhoea
Al - constipation
thus, they are combined to minimise impact on bowel function
what are the cautions associated with taking antacids?
- not to take within 2h of other medication!!! (as it affects absorption of other medications)
- avoid long term use in patients with renal insufficiency
name an example of a H2 receptor antagonists
famotidine
what is the MOA of famotidine
competitive inhibitor of H2 receptors on parietal cells - suppresses the acid secretion
when is the best time to take famotidine?
before sleep at night - inhibits nocturnal acid secretion
what are the adverse effects associated with taking famotidine
headache, nausea, dry mouth
severe effects - tachycardia, blur vision and msk pain
what are the adverse effects associated with taking cimetidine
headache, nausea, diarrhoea, fatigue
mental confusion in critically ill patients or patients with renal/hepatic dysfunction
name an example of a PPI
omeprazole
esomeprazole
what is the MOA of PPI
enteric coated formulation - protect against stomach acid
absorbed in intestines
inhibits gastric acid secretion
what is the duration of action of PPI
given 1h before meal, once a day
takes 3-4 days to fully inhibit acid secretion
what are the adverse effects associated with PPI
nausea, diarrhoea, headaches
increased risk of enteric c diff, intestinal colonisation with multi-drug resistant organisms
what is the MOA for sucralfate - gastric mucosal protection
stimulates mucosal prostaglandin and bicarbonate secretion
when is sucralfate administered
empty stomach - at least 1h before meal
what are the adverse effects associated with sucralfate
constipation
impairs absorption of other drugs
what is the MOA of bismuth compounds
- Bismuth forms a protective layer protecting ulcers from acid and pepsin
- Stimulates mucus and bicarbonate secretion
- Direct anti-microbial activity against H. pylori
what are the adverse effects associated with bismuth compounds
- blackening of stool and darkening of tongue
- prolonged use may rarely produce bismuth toxicity - resulting in encephalopathy (ataxia, headaches, seizures)
which patients should avoid using bismuth compounds
patients with renal insufficiency
what is the MOA of misoprostol
binds to PGE2 receptors
@ low dose - cytoprotective: promotes bicarbonate and mucus secretion
@ high dose - antisecretory: inhibits gastric acid secretion
what are the adverse effects associated with misoprostol
abdo pain
diarrhoea
abortion - uterine contraction
bone pain and hyperostosis (excess bone growth)
why is the use of misoprostol limited today?
adverse effects
multiple daily dosing - non compliance
potential abuse for abortifacient (to cause abortion)
what is triple therapy for H pylori
PPI + 2 antibiotics (claritho + amox)
what is the MOA for PPI in triple therapy
direct antimicrobial properties
raises intra-gastric pH lowering the minimum inhibitory concentration of abx against H pylori
what is quadruple therapy?
1 bismuth + 2 abx + 1 PPI or H2 antagonists
should PPI be continued after completion of triple therapy
yes
4-8 weeks for duodenal ulcers
8-12 weeks for gastric ulcers
what are the side effects associated with triple therapy?
diarrhoea
nausea
vomiting
