Drugs and the Gut

Question 1

Define “antagonist”

Answer 1

A drug or chemical which blocks the physiological response of another by binding and blocking its receptor

Question 2

Define “agonist”

Answer 2

A drug or chemical which produces a physiological reaction by binding to its receptor

Question 3

Define “irreversible binding”

Answer 3

An irreversible antagonist binding to a receptor which cannot be displaced

Question 4

Define “side effect”

Answer 4

An effect which occurs additionally to the desired effect

Question 5

What two places can peptic ulcers arise?

Answer 5

Stomach ulcer

Duodenal ulcer

Question 6

State some symptoms of having ulcers

Answer 6

Pain in abdomen, neck, back; Bleeding; Indigestion; Heartburn; Loss of apetite; Vomiting

Question 7

State two broad mechanisms of how peptic ulcers are caused

Answer 7

Bacterial Infection

NSAIDs

Question 8

What are the names given to the three cells involved in gastric secretions?

Answer 8

Neck cells
Chief cells
Parietal / Oxyntic cells

Question 9

What three regions of the stomach are the Neck cells found in?

Answer 9

Cardiac, Pylorus, Fundus

Question 10

Where are Chief cells found in the stomach?

Answer 10

Fundus

Question 11

Where are Parietal / Oxyntic cells found in the stomach?

Answer 11

Fundus

Question 12

What kind of gastric secretion do Neck cells secrete?

Answer 12

Mucus

Question 13

What kind of gastric secretion do Chief cells secrete?

Answer 13

Proteolytic enzymes

Question 14

What kind of gastric secretion do Parietal / Oxyntic cells secrete?

Answer 14

HCl

Question 15

What do the gastric glands secrete?

Answer 15

Gastric juice (HCl, enzymes, mucus)

Question 16

To heal the peptic ulcer, we need a pH of…?

Answer 16

Greater than 3

Question 17

Which bacteria causes Stomach ulcers?

Answer 17

Gram negative Heliobacter pylori

Question 18

How does H. pylori cause ulcers?

Answer 18

H. pylori secretes urease to produce ammonia and H2C03.

Question 19

What are the four types of histamine receptor, and which one is the most important for targeting treatment for ulcers?

Answer 19

H1, H2, H3, H4

H2 Receptor

Question 20

Give three examples of H2 antagonists

Answer 20

Cimetidine
Ranitidine
Famotidine

Question 21

State three examples of PPIs

Answer 21

Omeprazole
Lansoprazole
Pantoprazole

Question 22

Why are PPIs very long lasting?

Answer 22

1. Accumulation of the drug in the parietal cell canaliculi

2. Irreversible nature of proton pump inhibition

Question 23

How are PPIs prodrugs?

Answer 23

They have a bicarbonate / enteric coat which prevents rapid exposure to stomach HCl

Question 24

How can you treat H. pylori? What are the combinations?

Answer 24

Amoxicillin + Clarithromycin

Amoxillicin + Metronidazole

Combined therapy with PPI

Question 25

Give examples of NSAID drugs which can cause Ulcers

Answer 25

Aspirin Ibuprofen Naproxen

Question 26

How does NSAIDs cause ulcers?

Answer 26

It is a systemic drug, targeting COX-1 and COX-2 enzymes

Question 27

What is often given with NSAIDs to inhibit the adverse affects of ulcer formation?

Answer 27

Misoprostol, which is a Prostaglandin mimetic

Question 28

Where is the vomiting centre located? What NT is it associated with?

Answer 28

In the brain (past the Blood Brain barrier), and acetylcholine

Question 29

Where is the Chemoreceptor trigger zone, and why is its location important?

Answer 29

It is located outside the blood brain barrier, and therefore is susceptible to drugs

Question 30

The CTZ is linked to what, to regulate balance? Via which NTs?

Answer 30

The vestibular apparatus, and via Ach and Histamine

Question 31

The vomiting centre cannot be induced by drugs but can be induced by...?

Answer 31

Pain Sight Smell

Question 32

Give example of a Acetylcholine muscarinic receptor antagonist used to treat travel sickness

Answer 32

Hyoscine

Question 33

State three examples of drugs used as a H1 receptor antagonist (Clue: -ine) to counteract sickness (anti-emetic)

Answer 33

Cyclizine Cinnarizine Promethazine

Question 34

What class of drugs are typically used to treat chemotherapy related nausea?

Answer 34

5-HT3 receptor antagonists