Anti-emetics

Question 1

What are the steps in emesis ?

Answer 1

1. nausea, salivation and sweating
2. retrograde peristalsis
3. deep inspiration
4. closure of glottis
5. adbo muscles contract
6. LOS relaxes

Question 2

what make the chemical trigger zone activate ?

Answer 2

Sensory afferents via midbrain
direct triggers
vestibular nuclei
visceral afferents from gut

Question 3

what drugs act on the vestibular nuclei ?

Answer 3

Muscarinic receptor antagonists

H1 receptor antagonists

Question 4

Name 1 Muscarinic antagonist / anti-spasmodic drug

Answer 4

hyoscine hydrobromide

Question 5

how does hyoscine hydrobromide work ?

what are its uses/benefits ?

Answer 5

competitive blockade of M ACh receptors (nonspecific) in vestibular nuclei and CTZ

People who cant take tablets
motion sickness
bowel obstruction

Question 6

what are the side effects of hydroscine hydrobromide ?

Answer 6

sedation
memory problems
glaucoma
dry mouth and constipation

Question 7

How do H1 receptor antagonists work ?

Answer 7

acts on vestibular nuclei by inhibiting Histaminergic signals from vestibular system to the CTZ in medulla

Question 8

name 3 H1 receptor antagonists

Answer 8

Cyclizine - not suitable for elderly or children 
Levomepromazine 
Clinnirazine 
promethazine 
diphenhydramine

Question 9

what are side effects of clinnirazine ?

Answer 9

H1 antagonist
Sedation , excitation , Antimuscarinic (dry mouth, constipation, urinary retention)
cardiac toxicity

Question 10

what agents act on visceral afferents in the gut ?

Answer 10

5HT3 receptor antagonists

D2 Receptor antagonists

Question 11

where is serotonin produce in the gut ?
what is it stimulated by ?
what is the effect of serotonin on the Gut ?

Answer 11

enterochromaffin cells 
parasympathetics
SM contraction = increases motility 
Increases gut secretions 
regulates appetite

Question 12

What are the main functions of 5ht3 Receptor antagonists ?

Answer 12

centrally- inhibits the CTZ

Peripheral - reduces GI motility / secretions

Question 13

name 2 5HT3 antagonists

Answer 13

Ondansetron , Granesitron and palonosetron

1st line treatment

Question 14

what are the side effects of Ondansetron ?

Answer 14

uncommon

Constipation , headache , elevated LFTs, long QT syndrome , dystonia , parkinsonism

Question 15

name a D2 receptor antagonist specific to viscreal afferent of the guts

Answer 15

Metacloperamide

domperidone

Question 16

how does Metaclopramide work ?

Answer 16

increase ACh at M receptors in Gut =
promotes gastric emptying by:
Increasing tone at LOS and amplitude of gastric contractions
decrease tone of pylorus = increased peristalsis

Question 17

what are D2 antagonists used for ?

Answer 17

GORD , ileus

Question 18

what are the side effects of metaclopramide ?

Answer 18

Galactorrhoea via prolactin release

Dystonia , parkinsonism

Question 19

what is domperidone alternative use ?

what is its main side effect?

Answer 19

improving lactation for mothers

sudden cardiac death

Question 20

what drugs act on the CTZ ?

Answer 20

5HT3 receptor antagonists
H1 antagonists
Muscarinic antagonists
D2 . antagonists
Corticosteroids 
cannabinoids
NK1 antagonists

Question 21

name 2 anti psychotics/ d2 antagonists

Answer 21

Haloperidol
Levomepromazine
chlorpromazine
Prochlorperazine

Question 22

what D2 antagonists is used in pregnancy ?

Answer 22

prochlorperazine

Question 23

what is haloperiodol used for ?

Answer 23

chemotherapy and palliative care

Question 24

name 2 corticosteroids

Answer 24

Dexamethasone , methylprednisolone

Question 25

what are corticosteroids good for ?

Answer 25

periop nausea and vomiting chemotherapy palliation

Question 26

what are side effects of methylprednisolone ?

Answer 26

Insomnia, increase appetite and blood sugar

Question 27

Name 1 cannabinoid

Answer 27

Nabilone

Question 28

what are side effects of nabilone?

Answer 28

dizziness / drowsiness

Question 29

how do NK1 receptor antagonists work ?

Answer 29

prevent action of substance P at CTZ and in peripheral nerves boosts effects of 5HT3 antagonists = Anxiolytic and antipressent properties

Question 30

name 2 NK1 antagonists

Answer 30

aprepitant fosaprepitant netupitant

Question 31

what are the side effects of NK1 antagonists ?

Answer 31

Headaches , diarrhoea , constipation and stevens-johnson

Question 32

name 2 prokinetics

Answer 32

domperidone | metaclopramide

Question 33

what drugs to use for motion sickness ?

Answer 33

1st line Hyoscine hydrobromide (drowsiness) | Cinnirazine - fewer sides effects (vestibular )

Question 34

what procedure can you use instead of drugs for antiemetics ?

Answer 34

Nasogastric tube

Question 35

when shouldn't you use Domperidone ?

Answer 35

prokinetic - | risk of obstruction or perforation

Question 36

what are the 4 medications of anti-emetic GI patholgies and their MOAs?

Answer 36

``` Odndanserton - 5HT3 antagonist Cyclizine - H1 antagonist then add Dexamethasone - Corticosteroid Metacloperamide- D2 antagonist ```

Question 37

What causes hyperemesis gravidrum ? what complications can occur ? what puts you at more risk ?

Answer 37

rapid rise in bHCG in the CTZ Dehyrdation , weight loss, electrolyte imbalance and urinary ketones multiple pregnancies

Question 38

Name the 4 drugs you use for hyperemesis Gravidum ?

Answer 38

Promethazine (h1) or prochlorperazine (D2) Add Metaclopramide (D2) Ondanserton

Question 39

what drugs do you use for low risk chemo?

Answer 39

Dexamethasone

Question 40

what drugs do you use for moderate risk chemo?

Answer 40

Dexamethasone | Ondanserton

Question 41

what drugs do you use for high risk chemo?

Answer 41

Dexamethasone Ondanserton Aprepitant

Question 42

what can put you in risk of emesis in terms of anaesthetics and surgery ?

Answer 42

``` use of general Volatile/ NO gases post op opoids duration of surgery Laparoscopic ```

Question 43

what is general rule for anti-emetic post op care in terms of low, moderate and high risk ?

Answer 43

``` Low = wait and see moderate = 1 or 2 antiemetics high = 2 or more antiemetics ```

Question 44

what should you do if prophylactic anti emetic care does not work ?

Answer 44

use a different class of anti emetic

Question 45

how can you describe diarrhoea? what can you use ?

Answer 45

Consistency , frequency compare to normal bowel habitat Bristol stool chart

Question 46

how do opioid agonists help with diarrhoea ?

Answer 46

decreases tone of Longitudinal and circular Smooth muscle reduce peristalsis but increase segmental contraction = more time supresses gastrocolic reflex

Question 47

Name 2 opioids and which one is specific to the myenteric plexus ?

Answer 47

Loperamide - gut specific Codeine morphine

Question 48

What are the side effects of Opioids ?

Answer 48

paralytic ileus nausea and vomiting sedation and addiction

Question 49

what should you avoid when you have diarrhoea ?

Answer 49

Caffeine , sorbitol , fatty/ spicy foods and fizzy drinks | re instate a balanced intestinal flora

Question 50

What should you do if you are constipated ?

Answer 50

Drink more water increase fibre intake regular excercise toilet routine and positioning

Question 51

name 2 osmotic laxatives

Answer 51

Lactulose, Macrogol

Question 52

how does Lactulose work ?

Answer 52

draws fluids in

Question 53

how does macrogols work ?

Answer 53

retain the fluid they came in with

Question 54

name 2 stimulant laxative s

Answer 54

Docusate sodium, Senna, Sodium picosulfate

Question 55

how does Docusate sodium work?

Answer 55

stimulant and stool softener

Question 56

how does glycerin work ?

Answer 56

causes rectal irritation and lubrication

Question 57

Name the bulk forming laxatives

Answer 57

Ispaghula husk, Methylcellulose

Question 58

how do stool softeners work and name 2

Answer 58

Decrease surface tension of stool increase penetration of fluid into stool Arachis oil, Glycerol suppository