GI drugs

Question 1

Which of the following mechanisms does NOT lead to a an increase in proton-pump activity.

a. Ach stimulating muscarinic receptors
b. Gastrin stimulating CCK2 receptors
c. Histamine stimulating H2 receptors
d. PGE2 stimulating EP3 receptors

Answer 1

d. PGE2 stimulating EP3 receptors

Question 2

What is the main role of prostaglandins in the GI?

Answer 2

• produce more substrates to make up the mucosa to protect stomach lining

Question 3

What are the 2 ways in which gastrin stimulates the parietal cell? Which one is more common?

Answer 3

• gastrin stimulates ECL cell to produce more histamine*

- gastrin stimulates CCK2 cell

Question 4

The feedback loop in the GI is mostly mediated by what?

Answer 4

• Gastrin

Question 5

When are the parietal cells most activate?

Answer 5

• after a meal

Question 6

What is the difference between lumen pH with an empty stomach and post prandial?

Answer 6

• basal acid = 1-2

- post pandrial = 4-5

Question 7

What antibiotics may be prone to interactions with antacids?

Answer 7

• FQs

Question 8

What is the mechanism of Antacids?

Answer 8

• rapid local neutralization of acid in the stomach

Question 9

What adverse effects are seen with antacids? What elements correlate to each?

Answer 9

• diarrhea = Mg
• constipation = AI
• abdominal distension = Ca2+

Question 10

If a patient is taking an antacid and is complaining of side effects what do you need to do?

Answer 10

• find out exactly what antacid they are taking (ask for the bottle)
• take home message from the graph

Question 11

What are the 3 indications for bismuth compounds? (Pepto-Bismol)

Answer 11

• protect stomach lining
• slow down intestinal transit (diarrhea)
• can be useful to treat traveler’s diarrhea (antibacterial)

Question 12

What are the 4 adverse effects listed with bismuth compounds (Pepto-Bismol)?

Answer 12

• constipation
• darkening of tongue/stool
• avoid if aspirin allergy
• drug interactions

Question 13

Which of the cytoprotectants is prescription only?

• Bismuth Compounds
• Sucralfate
• Misoprostol

Answer 13

• Sucralfate

Question 14

What are the 2 potential uses for sucralfate?

Answer 14

• acid-peptic disease

- stress ulcer prophylaxis (patient on mechanical ventilator)

Question 15

Which animal is at risk for stress ulcers?

Answer 15

horses

Question 16

Why may sucralfate be a better drug for stress ulcer prophylaxis then a PPI or H2 antagonist?

Answer 16

• does not change pH in stomach so doesn’t change bacteria in stomach = less risk of aspiration pneumonia in patients who are ventilated

Question 17

What is the most common adverse effect of sucralfate?

Answer 17

• constipation

Question 18

Which patients are at greatest risk of stress ulcer?

Answer 18

• patients intubated in ICU

* give stress ulcer prophylaxis = Misoprostol

Question 19

This cytoprotectant is a prostaglandin E1 analog.

• Bismuth Compounds
• Sucralfate
• Misoprostol

Answer 19

• Misoprostol

* stimulates secretion of mucin and bicarb

Question 20

What is the primary concern in a pregnant patient using misoprostol?

Answer 20

• increased uterine contractility = medical termination OR labor induction

Question 21

What is the major side effect with misoprostol?

Answer 21

• diarrhea

Question 22

What is the mechanism of H2 -receptor antagonists (e.g. cimetidine) ?

Answer 22

• compete with histamine for binding to H2 receptors on parietal cells

Question 23

What are the 3 indications for a H2-receptor antagonist (e.g. cimetidine)?

Answer 23

• uncomplicated GERD
• gastric/duodenal ulcers
• stress ulcer prophylaxis

Question 24

What are the 3 side effects unique to cimetidine? (H2 antagonists)

Answer 24

• short acting
• inhibitor of CYP-450
• gynecomastia in men; galactorrhea in women

Question 25

What is the reason Ranitidine is not on the market anymore?

Answer 25

- has the potential to form NDMA which is carcinogenic

Question 26

What agents are the most potent of the acid suppressive therapies?

Answer 26

- PPIs (e.g. Omeprazole) | * most potent at raising pH!!

Question 27

When is it best to take PPIs in relation to eating?

Answer 27

- 30 to 60 minutes prior

Question 28

Why is PPIs enteric coated formulations?

Answer 28

- parent compound is unstable in acid

Question 29

What is the mechanism of action of PPIs?

Answer 29

- irreversibly bind to and inactivate H-K ATPase

Question 30

What is the half life, onset, and duration of effect of PPIs (e.g. omeprazole)?

Answer 30

- half life = 1-2 hours - onset = 2-5 days - duration = 24-48 hours

Question 31

What are the 4 indications for PPIs?

Answer 31

- gastric and duodenal ulcers - GERD - Barrett's esophagus - Zollinger Ellison syndrome

Question 32

What happens to gastrin with PPI administration?

Answer 32

- gastrin will be hyper-secreted | * can lead to hypertrophy of ECL

Question 33

PPI reduces the absorption of what 3 vitamin/minerals?

Answer 33

- B12 - Calcium - Magnesium

Question 34

What is the association between Clopidogrel (Plavix) and PPIs?

Answer 34

- PPIs inhibit 2C19 enzyme = decrease efficacy of Clopidogrel d/t it being a pro drug

Question 35

What is the major adverse effect of withdrawing PPIs?

Answer 35

- reflex hyperacidity | * need to taper down

Question 36

What is the primary therapy regimen for H. Pylori?

Answer 36

- Bismusth subsalicylate - Metronidazole - Tetracycline (10-14 days) *plus high dose acid suppressive therapy (continued 2+ weeks after BMT)

Question 37

What are the adverse effects seen in the primary treatment regiment for H. Pylori (BMT)? (4)

Answer 37

- nausea - diarrhea - taste disturbances - allergic reactions