GI: Drugs that influence acid secretion

Question 1

What four classes of drugs influence gastric acid secretion?

Answer 1

Muscarinic receptor antagonists
Proton pump inhibitors
NSAIDS
H2 histamine receptor antagonists

Question 2

Which of these drugs act competitively?

Answer 2

Muscarinic antagonists

and H2 antagonists

Question 3

Which of these drugs act irrevesibly?

Answer 3

NSAIDS

Proton pump inhibitors

Question 4

Which of these drugs act by covalent modification?

Answer 4

Proton pump inhibitors

Question 5

What is the purpose of locally produced prostoglandins ?

Answer 5

Reduce acid secretion
Increase mucus bicarbonate
Increase mucosal blood flow

Question 6

What is a peptic ulcer?

Answer 6

Any ulcer in an area where the mucosa is exposed to hydrochloric acid and pepsin

Question 7

How can NSAIDs trigger or exacerbate a peptic ulcer?

Answer 7

Reduce prostaglandin formation because they inhibit COX

Question 8

Name a drug that can reduce gastric damage due to long term NSAID treatment?

Answer 8

Misoprostol
Inhibits gastrin production
Maintains secretion of mucus and bicarbonate

Question 9

What three drugs can be used to reduce gastric acid secretion?

Answer 9

Proton pump inhibitors
H2 antagonists
Muscarinic receptor antagonists

Question 10

Name a proton pump inhibitor?

Answer 10

Omeprazole

Question 11

How do proton pump inhibitors work?

Answer 11

Inhibit the ACTOVE pump .

At the cannaliculi they are activated to sulfenamide and thus covalent modification of proton pumps occurs

Question 12

Decribe how omeprazole is a prodrug

Answer 12

Undergoes a conformational change at lower pH’s and becomes more active

Question 13

When should omeprazole be administered?

Answer 13

When proton pumps are active

Question 14

Why are proton pump inhibitors long acting despite short half life?

Answer 14

They inhibit the pump irreverssibly

Question 15

What diseases are proton pump inhibitors used to treat?

Answer 15

Peptic ulcers
GORD
Zollinger Ellison syndrome

Question 16

Name two histamine H2 receptor antagonists?

Answer 16

ranitidine

cimetidine

Question 17

How does ranitide work?

Answer 17

Competiviely and revesibly blocks the H2 receptors and this blocs the histamine mediated component of acid secretion

Question 18

Name two mucosal strengtheners?

Answer 18

Sucralfate

Bismuth chealate

Question 19

How does sucralfate work?

Answer 19

Compex of aluminium hydroxide which binds to the ulcer base forming a complex gel with mucus - mucosal barrier against acid and pepsin is formed
Increases mucosal blood flow, mucus, bicarbonate and prostaglandin production

Question 20

When is bismuth chealte particularly used?

Answer 20

With H pylori infection in combo with antibiotics and H2 antagonists

Question 21

When does sucralfate work?

Answer 21

In acidic conditions- releases aluminium to acquire a strong negative charge

Question 22

What are antacids?

Answer 22

Neutralise gastric acid for symptomatic relief eg gaviscon etc

Question 23

Name two antacids?

Answer 23

Magnesium hydroxide

Aluminium hyroxide

Question 24

Which antacid can cause diarrhoea?

Answer 24

Magnesium

Question 25

Which antacid can cause constipation?

Answer 25

Aluminium

Question 26

What antibiotics would be used to eradicate h.pylori?

Answer 26

Clarithromycin and either amoxicillin or metronidazole

Question 27

Name two drugs that increase motility?

Answer 27

Domperidone

Metoclopramide

Question 28

How does domperidone work?

Answer 28

Increases the tone of the lower eosophageal sphincter, increased gastric emptying and enhances duodenal peristalsis

Question 29

When is domperidone used?

Answer 29

GORD

gastroparesis

Question 30

When is metclopramide used?

Answer 30

Greatly increase gastric emptying

used in gord and gastric empyting disorders