Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology > Drugs Affecting Gut Motility > Flashcards

Drugs Affecting Gut Motility Flashcards

1
Q

What are the types of physiological control of gut motility

A

Myogenic
Neurological
Hormonal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is myogenic control of gut motility

A

Rhythmic contractions of intestinal smooth muscle
Interstitial cells of Cajal act as pacemaker cells
Depolarisations spread through gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is neuronal control of gut motility

A

Enteric Plexus - network of autonomic fibres in intestinal wall
Cholinergic nerves increase force of contraction
Non-adrenergic inhibitory nerves decrease contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is hormonal control of motility

A

Peptide hormones secreted by endocrine cells in intestinal mucosa
CCK
Secretin
Gastrin
Paracrine - prostaglandin, histamine, somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the steps of vomiting reflex

A

Contraction of pyloric sphincter
Relaxation of cardia and oesophagus
Contraction of abdominal wall and diaphragm
Expulsion of gastric contents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are triggers of vomiting reflex

A

RICP
Vestibular apparatus : rotational movement
Chemoreceptor Trigger Zone: toxins, Drugs, electrolytes
Higher cortical centres: pain, sight, smell
GI tract: stretch, inflammation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is vomiting centre

A

Area in medulla responsible for control+coordination of muscles involved in vomiting reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Area Postrema

A

Part of vomiting centre containing CTZ
Located in base of 4th ventricle
Thus Outside BBB and exposed to blood vomiting triggers in peripheral circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are neurotransmitters involved in vomiting reflex

A

Vestibular apparatus: H1 receptor
CTZ: D2, 5HT3
GI: D2
Vomiting centre: ACh, H1, 5HT3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are types of antiemetic drugs

A 
D2 antagonist 
5HT3 antagonist
ACh antagonist 
H1 antagonist 
Cannabinoids 
Benzodiazepines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Give examples of D2 antagonists

A

Domperidone
Metoclopromide
Phenothiazine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is mechanism of action of D2 antagonists

A

Antagonise D2 receptor at Area postrema

Antagonise D2 at stomach - slow gastric emptying

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are indications of D2 antagonists

A

Acute N+V (esp if L-dopa induced)

PONV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are side effects of D2 antagonists

A

Galactorrhoea (loss of dopaminergic inhibition of prolactin release)
Dystonia (rare)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are PK properties of D2 antagonists

A

Oral, PR
Extensive first pass metabolism
Does not cross BBB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give examples of 5HT3 antagonists

A

Ondansetron

Granisetron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is mechanism of action of 5HT3 antagonists

A

Antagonise 5HT3 at area postrema

Antagonise 5HT3 receptors of vagus afferent fibres in GIT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are indications of 5HT3 antagonists

A

Chemotherapy (1st line)
Radiation sickness
PONV (esp opioid induced)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are side effects of 5HT3 antagonists

A

Headache
Constipation
Flushing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How are 5HT3 antagonists administered

A

IV

Enhanced effect if given with dose of corticosteroids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is mechanism of action of metoclopramide

A

Antagonise D2 at area postrema
Antagonise D2 at stomach - slow gastric emptying
Anticholinergic (GI)
Antagonise 5HT3 at vagal afferent fibres of GIT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are indications of metoclopramide

A

Acute N+V (first line)

PONV (gastric cause)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is metoclopramide administered

A

Oral

TDS - T1/2 4hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are side effects of metoclopramide

A

Extrapyramidal side effects - CI in PD

Galactorrhoea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Give examples of ACh antagonists

A

Hyoscine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is mechanism of action of ACh antagonists

A

Antagonise mAChR at vestibular apparatus

Anticholinergic at GIT - inhibit gastric secretions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are indications of ACh antagonists

A

Motion sickness

N+V in Obstruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are side effects of ACh antagonists

A

Systemic anticholinergic effects

29
Q

Give examples of H1 antagonists

A

Cyclizine

Promethiazine

30
Q

What is mechanism of action if H1 antagonists

A

Antagonise H1 at vomiting centre

31
Q

What are indications of H1 antagonists

A

Acute N+V

32
Q

What are side effects of H1 antagonists

A

Sedation

QT prolongation

33
Q

What are principles of management of constipation

A

Lifestyle: increase fluids, fibre, exercise
Treat underlying cause: dehydration, DM, PD, opioids, diuretics, anticholinergics
Pharmacological: laxatives

34
Q

What are the types of laxatives

A 
Stimulant (soft stool)
Osmotically active (hard stool)
Bulking agent (hard stool) 
Faecal softeners (hard stool)
35
Q

Give examples of bulking laxatives

A

Ispaghula

Cellulose

36
Q

What is mechanism of action of bulking agents

A 
Insoluble agents draw water in
Bowel distension
Stimulate stretch receptors
Stimulate peristalsis 
Takes days to take effect
37
Q

What are indications of bulking agents

A

Hard stools

38
Q

What are side effects of bulking agents

A

Risk of obstruction - CI in adhesions and ulcers
Dehydration
Flatulence

39
Q

Give examples to faecal softeners

A

Arachis oil

Glycerol

40
Q

What is mechanism of action of faecal softeners

A

Lubricate stool

Assist evacuation of stool

41
Q

What are indications of faecal softeners

A

Hard stools
Adhesions
Anal fissure
Haemorrhoids

42
Q

What are side effects of faecal softeners

A

Safe

But not effective

43
Q

Give examples of osmotically active laxatives

A

Mg, Na salts
Lactulose
Macrogol (Movicol)

44
Q

What is mechanism of action of osmotically active laxatives

A

Draw water into lumen
Cause bowel distension
Stimulate stretch receptors in bowel wall
Stimulate peristalsis

45
Q

What are indications of Mg and Na salts

A

Urgent relief

Resistant constipation

46
Q

How is Mg and Na salts administered

A

PR

47
Q

What is mechanism of action of lactulose

A

Broken down by colonic flora into acetic and lactic acid
Acetic and lactic acid are osmotically active

Acetic and lactic acid bind+trap ammonia in gut

48
Q

What are indications of lactulose

A

1st line hospital constipation

Liver failure - prevent encephalopathy

49
Q

Give examples of stimulant laxatives

A

Senna
Codanthramer
Bisacodyl

50
Q

What is mechanism of action of stimulant laxatives

A

Stimulate enteric plexus
Stimulate peristalsis directly
Cause electrolyte and fluid retention, stimulate stretch receptors thus peristalsis

51
Q

What are indications of stimulant laxatives

A

Urgent treatment:
Surgical preparation
Impaction

52
Q

What are side effects of stimulant laxatives

A 
Abdominal cramps
Hypokalaemia 
Colonic atony (chronic use) 
Melenosis Coli (pigmentation; overuse)
53
Q

What are principles of management of diarrhoea

A

Treat cause: infection, IBD, IBS, bile, pancreatic enzymes
Supportive: fluids, electrolyte replacement
Anti-diarrhoea Drugs: for symptom relief

54
Q

Give examples of anti-motility drugs

A

Loperamide

55
Q

What is mechanism of action of loperamide

A 
Opioid analogue
Bind to opioid receptors on bowel wall
Decreased motility
Increased transit time
Increased water absorption 
Increased anal tone
56
Q

What are indications of loperamide

A

Chronic diarrhoea

57
Q

What are side effects of loperamide

A

Risk of toxic megacolon - CI in IBD

58
Q

What are types of anti-diarrhoea drugs

A

Anti-motility
Bulk-forming laxatives
Cholestyramine
Pancreatic enzymes

59
Q

What is mechanism of action of bulk forming agents for diarrhoea

A

Absorb water

60
Q

What are indications of bulk forming agents for diarrhoea

A

IBS with chronic diarrhoea+constipation

61
Q

What is mechanism of action of cholestyramine

A

Bile acid sequestration

62
Q

What are indications of cholestyramine

A

Diarrhoea secondary to bile acid malabsorption:
Crohn’s
Ileal resection

63
Q

Give examples of pancreatic enzymes

A

Pancreatase

64
Q

What are indications of pancreatase

A

Diarrhoea secondary to malabsorption from lack of pancreatic enzymes:
Chronic pancreatitis
Cystic fibrosis

65
Q

What is IBS

A

Chronic and relapsing disorder of GI function without physical/biochemical abnormality

66
Q

What is the diagnostic criteria of IBS

A

6 months of:
Abdominal pain relieved by defecation
Abdominal bloating
Change in bowel habit: Constipation, diarrhoea

67
Q

What are principles of management of IBS

A

Lifestyle: increase fluid, limit fibre, limit caffeine
Diarrhoea: loperamide
Constipation: ispaghul
Pain: peppermint oil, mebeverine

68
Q

What is mechanism of action of mebeverine

A

Antispasmodic agent
Anticholinergic effects on gut wall
Relax intestinal smooth muscle
Relieves pain from muscle spasms

Pharmacology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions