13.1 GI Motility Drugs Flashcards Preview

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Flashcards in 13.1 GI Motility Drugs Deck (50):
1

What can cause vomiting?

Problems with the vestibular system
Drug Induced - Post Op, Chemotherapy
Alcohol
Pregnancy
Unpleasant Stimuli - Smells
Infections - Salmonella
Raised ICP

2

What areas of the brain are involved in vomiting?

The Area Postrema
The Medullary Centres
The Vestibular Areas

3

What Neurotransmitters are involved in vomiting?

ACh
Histamine
Serotonin
Dopamine

4

What are the 4 classes of Drug we use to treat vomiting?

D2 antagonists
ACh (muscarinic) antagonists
5HT antagonists
Histamine antagonists

5

How do D2 antagonists work?
Examples:
When are they used?

Act on the area postrema

Metoclopramide
Post Operations, if GI cause, Chemotherapy, Migraines

Domperidone
It can increase gastric emptying
Use in acute cases e.g for Parkinsons Disease medication

6

ADRs of D2 antagonists?

Dystonia
Galactorrhoea
Gynacomastia (increased prolactin)

7

What are the stages of vomiting?

Stimulation of the Vomiting Centre - Area Postrema
Warning Signs - lightheaded, fast breathing, feel hot/sweaty, pale

Glottis closes, Soft Palate raises, pyloric sphincter contracts

Diaphragm and abdominal muscles contract, Cardia Relaxes

8

What is metoclopramide?
Pharmacokinetics?

D2 antagonist
Oral, IM, IV
Half life of 4 hours

9

What is Domperidone?
Pharmacokinetics?

D2 antagonist
Oral, Rectal
Doesn't cross BBB
Extensive 1st Pass Metabolism

10

How do 5HT antagonists work?
When used?

They work on the area postrema and periphery
They prevent vagal stimulation
Post Op
Chemotherapy

11

ADRs of 5HT antagonists?

Headaches
Constipation
Flushing

12

Example of a 5HT antagonist

Ondansteron

13

How do Histamine antagonists work?
When used?
Example?

Acute Cases e.g. MI
Cyclozine

14

How do ACh antagonists work?
When used?

Use in travel sickness
Short Half Life
Take 30 mins to take effect

15

ADRs of Histamine Antagonists?

Drowsiness
Long QT

16

ADRs of ACh antagonists?

Can become tolerant
Can cause systemic anti-muscarinic effects
Constipation
Bradycardia

17

What drugs do you use to treat constipation?

Bulk Forming Laxatives
Osmotically Active
Stool Softeners
Stimulants

18

How do you remember the 4 Constipation Drugs?

BOSS

19

Which treatments do you use if stool is found to be hard

Bulk Forming
Stool Softener (Faecal Softeners)

20

What laxative should you use if there is soft stool?

Stimulants

21

What lifestyle recommendations would you make to someone with constipation?

Fibre
Five a Day
Fluid
Alter Medication
Exercise

22

What conditions can cause constipation?

Pregnancy
Parkinsons
Diabetes
Dehydration

23

Which Drug do you not use if dehydrated?

Bulk Forming Agents - ispagula

24

Bulk Forming Agents - MoA?

Insoluble vegetable fibre, not absorbed, distends the intestine, stretch receptors causing peristalsis
It also draws H20 into the bowel, to distend as well

25

Bulk Forming Agents - When?

In pregnancy - it is safe!
Takes a few days to work and bring bowel function back to normal

26

Bulk Forming Agents - ADRs?

Flatulence

27

Bulk Forming Agents - Example

Ispagula

28

Bulk Forming Agents - Contraindications

Obstruction
Dehydration
Ulceration

29

Faecal Softeners - MoA and Example

Stay in the bowel, lubricate and soften stool
Glycerol
Arachnis Oil

30

Faecal Softeners - When use?

If cannot tolerate fibre
Very Safe
Haemorrhoids
Adhesions
Anal Fissures

31

Faecal Softeners - Contraindicated

In Obstruction

32

Faecal Softeners - Why not very good?

Not always effective
Normally suppository

33

Osmotically Active Laxatives - MoA?

Mg or Na Salts draw water into the bowel, distends the bowel causing peristalsis

34

Osmotically Active Laxatives - When use?

Instant relief needed
Before Surgery
Before Colonoscopy

35

Osmotically Active Laxatives - PK

Examples?
When use?

Very Potent
Fast Acting

Lactulose - liver failure
Macrogols - helps dehydration

36

Osmotically Active Laxatives - ADRs

Can cause obstruction

37

Stimulant Laxatives - MoA

Irritate the bowel mucosa, stimulates peristalsis and H2O to go into the bowel

38

Stimulant Laxatives - Examples?

Senna
Castor Oil

39

Stimulant Laxatives - When Use?

Overnight - takes 6/8 hours
Rapid Treatment

40

Stimulant Laxatives - Contraindicated

Not Long Term - melanosis coli
Hypokalaemia

41

Stimulant Laxatives - ADRs

Obstruction
Cramps
Atony
Hypokalaemia

42

How do you treat diarrhoea?

Drug treatments treat the symptoms not the cause
If can:
Treat underlying cause
Lifestyle Advice - no caffeine
Manage fluids and electrolytes

43

What drug classes would you treat diarrhoea with?

Anti-motility - opioids
Bulk Forming Agents
Bile Acid Sequestants
Pancreatic Enzymes

44

Anti-Motility Drugs - MoA?
Examples?

Act on Opioid receptors on the bowel to reduce movement
Codeine, Imodium

45

Anti-Motility Drugs - Containdicated

IBD - Causes Toxic Megacolon

46

Anti-Motility Drugs - Positives?

Increase Anal Tone
Reduce Reflex to Defaecate

47

Anti-Motility Drugs - When use?

Chronic Diarrhoea

48

Bulk Forming Agents, why use in diarrhoea?

Creates a more formed stool

49

When do you use Bulk Forming Agents?

IBS
Ileostomy
Diverticular Disease

50

When would you use a bile acid sequesterant?

In Crohns Disease
If Bile Salt Induced