constipation

Question 1

2 types of constpation

Answer 1

primary/functional

secondary/organic

Question 2

What must functional constipation include (2 or more of)?

Answer 2

• straining >25%
• lumpy/hard > 25%
• sensation of incomplete evacuation in >25%
• sensation of blockage/obstruction >25%
• manual maneouvres >25%
• < 3 per week
• loose stools rarely present without laxatives
• insufficient criteria for IBS

Question 3

How long must symptoms have been present for?

Answer 3

criteria fulfilled for 3 months

symptom onset > 6 months

Question 4

What causes organic constipation?

Answer 4

medication
metabolic diseases
neuropathies
myopathies

Question 5

When should further investigations take place?

Answer 5

unexplained constipation
abdominal pain
vomiting
blood/mucous
straining (tenesmus)
long standing
unresponsive to treatment

Question 6

What are the further investigations?

Answer 6

• colonic and anorectal manometry
• stool analysis
• flexible sigmoidoscopy
• colonoscopy

Question 7

What is 1st line therapy?

Answer 7

non-drug treatment

advice on diet and exercise

Question 8

What diet and lifestyle advice?

Answer 8

adequate fluid and fiber intake
regular exercise
no tea/coffee (diuretics, can worsen it)

Question 9

What is given in patients who don’t respond to lifestyle/diet changes?

Answer 9

laxatives

Question 10

laxatives don’t work

Answer 10

diagnostic testing

Question 11

main treatment for dyssynergic defecation

Answer 11

biofeedback therapy

Question 12

When is drug treatment given?

Answer 12

associated with illness
pregnancy
or
poor diet

Question 13

4 types of laxatives

Answer 13

bulk forming
stimulants
osmotic
faecal softeners

Question 14

4 examples of bulk forming agents

Answer 14

wheat bran
ispaghula husk
methylcellulose
sterculia

Question 15

When do bulking agents control fecal consistency?

Answer 15

IBS (diarrhoea)
ileostomy
colostomy

Question 16

3 MOA of bulk forming agents

Answer 16

1. hydrophilic action
2. proliferation of colonic bacteria
3. degradation of polysaccharides

Question 17

How does hydrophilic action work in bulking agents?

Answer 17

causes water retention in gut lumen

expands and softens feces

Question 18

Proliferation of colonic bacteria in bulking agents?

Answer 18

increases fecal bulk
stimulates colonic mucosal receptors
promotes peristalsis

Question 19

Degradation of polysaccharides in bulking agents?

Answer 19

degradation of polysaccharides in sterculia

to substances that have an osmotic laxative effect

Question 20

How long do bulking agents take to work?

Answer 20

24hrs

Question 21

When are bulking agents commonly used?

Answer 21

chronic constipation
diverticular disease
IBS

Question 22

When to avoid bulking agents?

Answer 22

if colon is atonic

fecal impaction

Question 23

4 examples of stimulant laxatives

Answer 23

senna
bisacodyl
danthron
sodium picoslfate

Question 24

2 components in Senna

Answer 24

sennosides A and B

anthrone glycosides

Question 25

What are sennosides A and B metabolised by gut bacteria to?

Answer 25

rheinanthrone

Question 26

What does rheinanthrone do?

Answer 26

increases COX 2 expression in macrophage cells increases prostaglandin E2 PEG2 decreases aquaporin 3 expression in large intestine and epithelial cells and stimulates peristalsis

Question 27

What does a dec in aquaporin 3 cause?

Answer 27

restricts water absorption | increases fecal water content

Question 28

What is bisacodyl hydrolysed BY?

Answer 28

hydrolysed by intestinal brush border enzymes and colonic bacteria

Question 29

Active metabolite of bisacodyl

Answer 29

BHPM

Question 30

How does BHPM work?

Answer 30

directly on colon mucosa stimulates nerve endings in intestine/rectum walls to produce peristalsis causes defecation

Question 31

What is a contact laxative?

Answer 31

increases fluid and salt secretion

Question 32

onset time for stimulant laxatives?

Answer 32

8-12 hours

Question 33

when should stimulants be taken

Answer 33

at bed time

Question 34

stimulant laxatives suppositories onset time

Answer 34

20 - 60 mins

Question 35

Can stimulant laxatives be used in pregnancy?

Answer 35

no | can cause uterine contraction

Question 36

chronic use of stimulant laxatives

Answer 36

atonic colon

Question 37

6 examples of osmotic laxatives

Answer 37

``` Mg salts lactulose lacitol PEG sodium citrate enemas phosphate enemas ```

Question 38

How do osmotic laxatives work?

Answer 38

retain fluid in the colon by osmosis

Question 39

time onset for phosphate enemas

Answer 39

30 mins

Question 40

when are phosphate enemas used

Answer 40

prior to surgery or sigmoidoscopy

Question 41

time onset of lactulose/lacitol (sugars)

Answer 41

up to 48 hours

Question 42

example of softener

Answer 42

docusate sodium

Question 43

What is docusate sodium?

Answer 43

a surfactant

Question 44

How do softeners work?

Answer 44

decrease surface tension and emulsification of fecal matter allows water to penetrate and mix with stool softens the stool

Question 45

When can rectal preparations of softeners not be used?

Answer 45

in haemorrhoids

Question 46

What drug can be used after 2 failed treatments?

Answer 46

libiprostone

Question 47

What is lubiprostone?

Answer 47

a bicyclic fatty acid derived from prostaglandin E1

Question 48

How does lubiprostone work?

Answer 48

activates ClC-2 chloride channel on apical aspect of GI epithelial cells produces Cl rich fluid secretions

Question 49

What is lubiprostone used to treat?

Answer 49

chronic idiopathic constipation in adults tried at least 2 laxatives from different classes at highest tolerated dose for at least 6 months failed to provide relief and opioid constipation