Drugs Affecting the Gastrointestinal System Flashcards Preview

Gastrointestinal > Drugs Affecting the Gastrointestinal System > Flashcards

Flashcards in Drugs Affecting the Gastrointestinal System Deck (43):
1

What are some causes of peptic ulcers?

H. pylori, NSAIds, smoking, caffeine, alcohol, glucocorticosteroids, bile

2

Why are prostaglandin E2 and I2 protective against ulcers?

The stimulate secretion of mucus and bicarbonate and increase mucosal blood flow to remove stray H+ ions

3

What is the action of H2 receptor antagonists?

Block effects of gastrin, acetylcholine and histamine on parietal cells

4

How do parietal cells secrete acid?

With a proton pump which exchanges H+ for K+ with an ATPase

5

What is omeprazole?

A proton pump inhibitor

6

What is esomeprazole?

A proton pump inhibitor

7

What is ranitidine?

An H2 receptor antagonist

8

What is magnesium hydroxide?

An antacid - used to neutralise stomach acid

9

What is a contraindication of antacids?

Kidney problems

10

What are some side effects of antacids?

diarrhoea and constipation

11

Why do antacids cause rebound acidity?

Because they stimulate gastrin release

12

What are cytoprotective agents?

They coat the ulcer site to protect it from the acid

13

What is hyoscine butylbromide?

a muscarinic receptor antagonist - to reduce motility

14

What is mebeverine?

a non specific muscle relaxant

15

What is misoprostol?

A synthethetic prostaglandin E analogue - to increase mucus secretion and mucosal blood flow and decrease acid secretion

16

What the contraindication of misoprostol?

Pregnancy - will induce motility in uterus and cause an abortion

17

What are other side effects of misoprostol?

colic and diarrhoea

18

What are two inputs to the vomiting centre?

the chemoreceptor trigger zone and the vestibular apparatus

19

What are the receptors for the chemoreceptor trigger zone to the vomiting centre?

D2 receptors and 5HT3 receptors

20

What are the receptors for the vestibular apparatus to the vomiting centre?

H1 receptors and muscarinic receptors

21

What is hyoscine hydrobromide?

a muscarinic receptor antagonist that crosses the blood blood brain barrier for motion sickness

22

What are the side effects of hyoscine hydrobromide?

anti SLUD - dry mouth, dry eyes, urinary retention, constipation

23

What is promethazine?

An H1 receptor antagonist for motion sickness (phenergen)

24

What is metoclopramide?

A D2 receptor antagonist for vomiting and nausea associated with the chemoreceptor trigger zone - also a weak 5HT3 antagonist and a potent 5HT4 agonist - facilitates gastric emptying via increased ACh (but not diarrhoea)

25

What is the effect of facilitating gastric emptying in metoclopramide?

changes the absorption of other drugs

26

What is prochlorperazine?

A D2 receptor antagonist for vomiting and nausea associated with the chemoreceptor trigger zone

27

What are the side effects of D2 receptor antagonists?

extra pyramidal side effects - motor movements like parkinsons and sometimes irreversible tardive dyskinesia

28

What is ondansetron?

A 5HT3 receptor antagonist - used for vomiting and nausea associated with the chemoreceptor trigger zone - blocks both receptors on the the chemoreceptor trigger zone and on vagal afferents which receive signals from the enterochrommaffin cells

29

What are the side effects of 5HT3 receptor antagonists?

very few - minor headache and constipation

30

What is aprepitant?

An NK1 receptor antagonist - a substance P antagonist - substance P is found in high concentrations in the vomiting centre in the brain

31

What is dexamethasone?

A glucocoritcosteroid used to treat nausea and vomiting although not technically an antiemetic

32

What is rabione?

A synthetic cannabinoid - used as an antiemetic

33

What is apomorphine?

A dopa receptor agonist - a very potent emetic

34

What causes constipation?

certain drugs e.g. opioids, lifestyle factors, inadequate dietary fibre intake, inappropriate bowel habits, inadequate activity, spinal injury, dementia, depression, hypothyroidism

35

Apart from constipation, when else are laxatives used?

Before a colonoscopy, hernias, prolapsed rectum

36

What are bulking agents?

indigestible vegetable fibre taken with water to stimulate normal reflex bowel movements

37

What is docusate?

A faecal softener - acts as an emulsifying agent

38

What is liquid paraffin?

A faecal lubricant - may cause loss of fat soluble vitamins

39

What is magnesium sulphate?

an osmotic laxative - causes osmotic fluid retention to get more mass and more distension

40

What is bisacodyl?

A stimulant laxative - precise mode of action not known but causes increased motility

41

What is senna?

A stimulant laxative - precise mode of action not known but causes increased motility - often used in combination with docusate

42

What is loperamide?

An opioid that doesnt cross the blood brain barrier used as an antidiarrhoeal

43

What is simethicone?

a defoaming polymer used to coalesce gas bubbles so they can be more easily passed