13.1 GI Motility Drugs Flashcards Preview

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Flashcards in 13.1 GI Motility Drugs Deck (50)
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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