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Flashcards in Pharmacology Deck (45):
1

What is a laxative?

Agents used to treat constipation

2

What are purgatives?

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

3

When should laxatives and purgatives not be used?

If there is a known bowel obstruction

4

In what way can laxatives be wrongly used?

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

5

What is laxative dependancy?

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

6

What can laxatives do?

Increase peristalsis and soften faeces causing or assisting evacuation

7

when should laxatives be used?

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

8

How do bulk laxatives work?

Retain water but increase bulk and peristalsis

9

How do osmotic laxatives work?

retain water but increase bulk and peristalsis

10

how do stimulant purgatives work?

increase water and electrolyte secretion, increase peristalsis and faecal softening

11

How do faecal softeners work?

increase water and electrolyte secretion, increase peristalsis and faecal softening

12

Give an example of bulk laxatives

methylcellulose which is given orally

13

give an example of osmotic laxatives

magnesium sulphates or hydroxide given orally

14

give an example of stimulant purgatives

bisacodyl given orally

15

give an example of faecal softners

docusate given orally

16

Treatment to reduce acid secretion in peptic ulcer disease?

PPIs e,g, omeprazole, iansoprazole, pantoprazole
Histamine H2 receptor antagonists

17

What is the mechanism of NSAIDs?

COX 1 inhibitor which reduces prostaglandin formation

18

What is the mechanism of PPIs?

Inhibits the active H+/K+ dependant ATPase

19

Which antiemetics are used in chemotherapy?

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

20

Which antiemetics are used in gastro-disorders?

Dopamine receptor antagonists

21

Which antiemetics are used for sever nausea and vomiting?

Phenothiazides

22

Which antiemetics are used for motion sickness?

Muscarinic acetylcholine receptor antagonists
Histamine H1 receptor antagonists

23

Which antiemetics are used against irritants of the stomach?

Histamine H1 receptor antagonists

24

Give an example of a 5-HT3 receptor antagonist

Ondansteron, palonosteron

25

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

Constipation and headaches

26

Give examples of dopamine receptor antagonists

Domperidone, metoclopramide

27

How does dopamine receptor antagonists work?

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

28

What are the side effects of dopamine receptor antagonists?

Disorder of movements

29

Give an example of an NK1 receptor antagonist

Aprepitant

30

How do NK1 receptor antagonists work?

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

31

What are NK1 receptors used with?

5-HT3 receptor antagonists

32

Give an example of a cannabinoid CB1 receptor antagonist

Nabilone

33

How to cannabinoid CB1 receptor antagonists work?

stimulate the CTZ - involves opiate receptors

34

What are the side effects of cannabinoid CB1 receptor antagonists?

Drowsiness, dizziness, dry mouth and mood changes

35

How do phenothiazines work?

Blockage of dopamine D2

36

Give examples of muscarinic acetylcholine receptor antagonists

Hyosine, scopolamine

37

What are the side effects of muscarinic acetyl choline receptor antagonists

Blurred vision, urinary retention, dry mouth and sedation

38

Give examples of histamine H1 receptor antagonists

Cyclizine, cinnarizine - i.e. anything ending in "zine"

39

How do histamine H1 receptor antagonists work?

Blockage of H1 receptors in the vestibular nuclei and NTS

40

Give an example of an H2 receptor antagonist?

Ranitidine

41

When are H2 receptor antagonists used?

Peptic ulcers, reflux, oesophagitis

42

When are PPIs used?

Peptic ulcers, GORD, acid hyper-secretion

43

Give examples of mucosal strengtheners

Sucralfate and bismuth chealate

44

How does sucralfate work?

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

45

What is bismuth chealate toxic to?

H. Pylori