antiulcer agents**

Question 1

which class reduces gastric acidity?

Answer 1

antacids, H2 receptor antagonist, PPI

Question 2

which class are mucosal protective agents?

Answer 2

sucralfate, misoprostol, bismuth compounds,

Question 3

what is the triple therapy for H. pylori eradication?

Answer 3

Clarithromycin, amoxicillion/metronidazole ( incase of penicillin allergy), PPI

2 antibiotic+ 1 PPI

Question 4

examples of antacids:

Answer 4

Sodium bicarbonate, calcium carbonate, magnesium hydroxide, aluminium hydroxide

Question 5

MOA of antacids:

Answer 5

● 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

Question 6

rate of neutralisation

Answer 6

NaHCO3 > CaCO3 > Mg(OH)2 > Al(OH)3

Question 7

rate of dissolution liquid vs tablet

Answer 7

liquid antacid better than tablet

Question 8

Adverse effects and cautions of antacids

Answer 8

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.

Question 9

List an example of H2 receptor antagonist

Answer 9

famotidine

Question 10

MOA of H2 receptor antagonist

Answer 10

blocks H2 receptors in parietal cells to decrease acid secretion

Question 11

efficacy of H2 receptor antagonist- famotidine

Answer 11

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

Question 12

Adverse effects of famotidine and ranitidine

Answer 12

headache, nausea, dry mouth
rare: tachycardia, blood dyscrasia, blurred vision, musculoskeletal pain

Question 13

adverse effects of cimetidine

Answer 13

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

Question 14

examples of PPI

Answer 14

omeprazole, esozmeprazole

most potent gastric acid secretion inhibitor drugs,

Question 15

MOA of PPI

Answer 15

inhibits H+-K+ATPase in parietal cells, irreversible block of proton pumps.
reduced gastric acid secretion
anti microbial activity against H. pylori.

Question 16

How to administer PPI?

Answer 16

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.

Question 17

how long does PPI take to fully inhibit acid secretion?

Answer 17

3-4 days

Question 18

efficacy of PPI in terms of pH

Answer 18

24 hour for intra gastric pH to increase to 3-4, pH will be more than 4 for abut 10-14 hours.

Question 19

Adverse effects of PPI

Answer 19

headache, nausea, flatulence, diarrhea, rash, dizziness.

long term use may result in osteoporosis.

Question 20

how to administer sulcrafate?

Answer 20

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,

Question 21

adverse effects of bismuth

Answer 21

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

Question 22

adverse effects of bismuth

Answer 22

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

Question 23

when do H.pylori thrive best?

Answer 23

pH 6-8

Question 24

how long does triple therapy last?

Answer 24

7-14 days

4-8 weeks for duodenal ulcers,

8-12 weeks for gastric ulcers.

Question 25

how to administer triple therapy?

Answer 25

ABx: BD, with or after food to reduce GI adverse effects.

PPI: BD, fast2 hours before, 30 mins before food.

Question 26

MOA of triple therapy:

Answer 26

antimicrobial+ raise pH to 3.5-5.5

Question 27

alternative to triple therapy

Answer 27

quadruple therapy

1 bismuth, 2 ABx, 1 PPI, H2 antagonist (10-14 days)

Question 28

side effects of triple therapy

Answer 28

diarrhea, n/v