antiulcer agents** Flashcards
(28 cards)
which class reduces gastric acidity?
antacids, H2 receptor antagonist, PPI
which class are mucosal protective agents?
sucralfate, misoprostol, bismuth compounds,
what is the triple therapy for H. pylori eradication?
Clarithromycin, amoxicillion/metronidazole ( incase of penicillin allergy), PPI
2 antibiotic+ 1 PPI
examples of antacids:
Sodium bicarbonate, calcium carbonate, magnesium hydroxide, aluminium hydroxide
MOA of antacids:
● DO NOT prevent gastric acid production rather they reduce gastric acidity
● Neutralize gastric acid to form salt and H2O
Some antacid preparations contain simethicone as an anti-foaming agent
○ Eases release of gas within the gastrointestinal tract via burping or flatulence
rate of neutralisation
NaHCO3 > CaCO3 > Mg(OH)2 > Al(OH)3
rate of dissolution liquid vs tablet
liquid antacid better than tablet
Adverse effects and cautions of antacids
Na+: fluid retension, hypertension, CHF
Ca2+: hypercalcaemia
} metabolic alkalosis
Aluminium: constipation
MG2+: osmotic diarrhea
when combined less likely to have diarrhea
Hco3- and co3- = Carbondioxide gas produces resulting in gastric distension, belching ( burping)
DONOT use long term for patients with renal insufficiency,
affect absorption of other medications, do not take within 2 hours of other meds.
List an example of H2 receptor antagonist
famotidine
MOA of H2 receptor antagonist
blocks H2 receptors in parietal cells to decrease acid secretion
efficacy of H2 receptor antagonist- famotidine
inhibits 60-70% of acid secretion.
effective at nocturnal acid secretion ( histamine)
modest effect on meal induced acid secretion ( gastrin and acetylcholine)
famotidine most potent at 20-50, 20mg doses only for 50% inhibition
Adverse effects of famotidine and ranitidine
headache, nausea, dry mouth
rare: tachycardia, blood dyscrasia, blurred vision, musculoskeletal pain
adverse effects of cimetidine
headache, n/v, diarrhea, constipation, faigue.
mental confusion in critically ill patients or in renal/hepatic dysfunction due to drug build up.
anti androgenic, inhibits estradiul metabolism, increases serum prolactin
men: genaecosmatia, impotence
female: galacctorrhoea - milky discharges
examples of PPI
omeprazole, esozmeprazole
most potent gastric acid secretion inhibitor drugs,
MOA of PPI
inhibits H+-K+ATPase in parietal cells, irreversible block of proton pumps.
reduced gastric acid secretion
anti microbial activity against H. pylori.
How to administer PPI?
empty stomach, 1 hour before meal, as bioavailability decreases 50% by food.
inactivate active pumps.
once daily, can last 24 hours due to irreversible blockage of proton pump.
how long does PPI take to fully inhibit acid secretion?
3-4 days
efficacy of PPI in terms of pH
24 hour for intra gastric pH to increase to 3-4, pH will be more than 4 for abut 10-14 hours.
Adverse effects of PPI
headache, nausea, flatulence, diarrhea, rash, dizziness.
long term use may result in osteoporosis.
how to administer sulcrafate?
1 hour before meals on empty stomach. limited use today, PPI and H2 antagonist are better.
used for stress related bleeding in critically ill patients,
adverse effects of bismuth
Harmless blackening of stool and reversible darkening of tongue
● Prolonged use may rarely produce bismuth toxicity resulting in encephalopathy (ataxia, headaches,
confusion, seizures)
○ Use only for short periods
○ Avoid in patients with renal insufficiency
adverse effects of bismuth
Harmless blackening of stool and reversible darkening of tongue
● Prolonged use may rarely produce bismuth toxicity resulting in encephalopathy (ataxia, headaches,
confusion, seizures)
○ Use only for short periods
○ Avoid in patients with renal insufficiency
when do H.pylori thrive best?
pH 6-8
how long does triple therapy last?
7-14 days
4-8 weeks for duodenal ulcers,
8-12 weeks for gastric ulcers.
