Pharmacology

Question 1

What is a laxative?

Answer 1

Agents used to treat constipation

Question 2

What are purgatives?

Answer 2

Drugs which deliberately cleanse or purge the GI tract by prompting evacuation i.e. used before surgery or before a colonoscopy

Question 3

When should laxatives and purgatives not be used?

Answer 3

If there is a known bowel obstruction

Question 4

In what way can laxatives be wrongly used?

Answer 4

If people use them to regulate bowel movements - cause laxative dependency
When used in eating disorders
Can disguise underlying disease

Question 5

What is laxative dependancy?

Answer 5

occurs because the laxative completely clear out the colon so they increase the time in which the person needs to defecate again

Question 6

What can laxatives do?

Answer 6

Increase peristalsis and soften faeces causing or assisting evacuation

Question 7

when should laxatives be used?

Answer 7

when straining is damaging
to clear the bowel before surgery or endoscopy
to treat drug induced constipation

Question 8

How do bulk laxatives work?

Answer 8

Retain water but increase bulk and peristalsis

Question 9

How do osmotic laxatives work?

Answer 9

retain water but increase bulk and peristalsis

Question 10

how do stimulant purgatives work?

Answer 10

increase water and electrolyte secretion, increase peristalsis and faecal softening

Question 11

How do faecal softeners work?

Answer 11

increase water and electrolyte secretion, increase peristalsis and faecal softening

Question 12

Give an example of bulk laxatives

Answer 12

methylcellulose which is given orally

Question 13

give an example of osmotic laxatives

Answer 13

magnesium sulphates or hydroxide given orally

Question 14

give an example of stimulant purgatives

Answer 14

bisacodyl given orally

Question 15

give an example of faecal softners

Answer 15

docusate given orally

Question 16

Treatment to reduce acid secretion in peptic ulcer disease?

Answer 16

PPIs e,g, omeprazole, iansoprazole, pantoprazole

Histamine H2 receptor antagonists

Question 17

What is the mechanism of NSAIDs?

Answer 17

COX 1 inhibitor which reduces prostaglandin formation

Question 18

What is the mechanism of PPIs?

Answer 18

Inhibits the active H+/K+ dependant ATPase

Question 19

Which antiemetics are used in chemotherapy?

Answer 19

5-HT3 receptor antagonists
Dopamine receptor antagonists
NK1 receptor antagonists
Cannabinoid CB1 receptor antagonists

Question 20

Which antiemetics are used in gastro-disorders?

Answer 20

Dopamine receptor antagonists

Question 21

Which antiemetics are used for sever nausea and vomiting?

Answer 21

Phenothiazides

Question 22

Which antiemetics are used for motion sickness?

Answer 22

Muscarinic acetylcholine receptor antagonists

Histamine H1 receptor antagonists

Question 23

Which antiemetics are used against irritants of the stomach?

Answer 23

Histamine H1 receptor antagonists

Question 24

Give an example of a 5-HT3 receptor antagonist

Answer 24

Ondansteron, palonosteron

Question 25

What are the side effects of 5-HT3 receptor antagonists?

Answer 25

Constipation and headaches

Question 26

Give examples of dopamine receptor antagonists

Answer 26

Domperidone, metoclopramide

Question 27

How does dopamine receptor antagonists work?

Answer 27

Centrally blocks D2 and D3 receptors in the CTZ snd helps control acid reflux in the oesophagus

Question 28

What are the side effects of dopamine receptor antagonists?

Answer 28

Disorder of movements

Question 29

Give an example of an NK1 receptor antagonist

Answer 29

Aprepitant

Question 30

How do NK1 receptor antagonists work?

Answer 30

antagonism of substance P which causes vomiting and is released by vagal afferents

Question 31

What are NK1 receptors used with?

Answer 31

5-HT3 receptor antagonists

Question 32

Give an example of a cannabinoid CB1 receptor antagonist

Answer 32

Nabilone

Question 33

How to cannabinoid CB1 receptor antagonists work?

Answer 33

stimulate the CTZ - involves opiate receptors

Question 34

What are the side effects of cannabinoid CB1 receptor antagonists?

Answer 34

Drowsiness, dizziness, dry mouth and mood changes

Question 35

How do phenothiazines work?

Answer 35

Blockage of dopamine D2

Question 36

Give examples of muscarinic acetylcholine receptor antagonists

Answer 36

Hyosine, scopolamine

Question 37

What are the side effects of muscarinic acetyl choline receptor antagonists

Answer 37

Blurred vision, urinary retention, dry mouth and sedation

Question 38

Give examples of histamine H1 receptor antagonists

Answer 38

Cyclizine, cinnarizine - i.e. anything ending in “zine”

Question 39

How do histamine H1 receptor antagonists work?

Answer 39

Blockage of H1 receptors in the vestibular nuclei and NTS

Question 40

Give an example of an H2 receptor antagonist?

Answer 40

Ranitidine

Question 41

When are H2 receptor antagonists used?

Answer 41

Peptic ulcers, reflux, oesophagitis

Question 42

When are PPIs used?

Answer 42

Peptic ulcers, GORD, acid hyper-secretion

Question 43

Give examples of mucosal strengtheners

Answer 43

Sucralfate and bismuth chealate

Question 44

How does sucralfate work?

Answer 44

binds to ulcer base and forms a complex gel with mucus to provide a mucosal barrier against acid and pepsin

Question 45

What is bismuth chealate toxic to?

Answer 45

H. Pylori