Constipation and laxatives

Question 1

1 example of a bulk forming laxative

Answer 1

ispaghula husk

Question 2

counselling points for bulk forming laxatives

Answer 2

• do not take before bed - BD full glass water - maintain good hydration

Question 3

pharmacology of bulk forming laxatives

Answer 3

• polysaccharides increase osmolality in gut when broken - water retention - water retention expands and softens stool - bulkier so distends colon and stimulates stretch receptors - ACh release which activates muscarinic receptors leading to peristalsis

Question 4

1 example of osmotic laxative

Answer 4

macrogol

Question 5

counselling points for osmotic laxatives

Answer 5

• 1-3 sachets daily in 125ml water - do not take other meds within 1 hour - 1-3 days for effect - can be high in sodium

Question 6

C/I for osmotic laxatives

Answer 6

hypertension, heart disease and renal failure

Question 7

pharmacology of osmotic laxatives

Answer 7

• poorly absorbed so increase water retention- absorbed into stool to soften them - contains magnesium

Question 8

how does magnesium in osmotic laxatives help

Answer 8

• magnesium triggers release of cholecystokinin (CKK) - increases intestinal secretions and colonic motility

Question 9

example of stool softeners

Answer 9

lactulose/docusate

Question 10

counselling points for lactulose

Answer 10

• very sweet - can cause bloating/colic - lactose intolerance!!!!- 2 days to effect

Question 11

counselling points for docusate

Answer 11

• 12-72 hours for tablet effect, 15 mins for suppository- well tolerated - good if struggle to increase fluid intake

Question 12

pharmacology of stool softeners

Answer 12

• work as surfactants to decrease surface tension - so water/fats can penetrate stool - softens so easier to pass

Question 13

example of stimulant laxative

Answer 13

senna, sodium Pico sulphate, bisacodyl

Question 14

counselling points for senna

Answer 14

• 8-12hr onset - short term - take in evening

Question 15

counselling for bisacodyl

Answer 15

• acts on small intestine - tablets 10-12hrs , suppos 20-60 mins

Question 16

pharmacology of stimulant laxatives

Answer 16

• Stimulate local reflexes of myenteric nerve plexus of the gut -increases propulsion - Increase secretion of water into the bowel

Question 17

pharmacology of senna

Answer 17

• anthraquinone - combines with sugars - glycosides - hydrolysed by colonic bacteria to release irritant anthracene glycoside derivatives, specifically sennosides A and B- have direct effect on myenteric nerve plexus - increasing smooth muscle activity

Question 18

example of a pamora

Answer 18

prucalopride

Question 19

counselling for pamoras

Answer 19

• selective serotonin 5ht receptor agonist - can cause headache and GI upset - increased doses do not improve response - 1-2 weeks for effect

Question 20

pharmacology of pamoras

Answer 20

• competitive agonists at intestinal mu-opioid receptors - prevent opioid activation for opioid related side effects

Question 21

pharmacology of prucalopride

Answer 21

• 5HT4 receptors present in GI tract, especially myenteric plexus * Activation leads to an increase in Ach * Increases rest and digest parasympathetic drive Increases peristalsis and propulsion

Question 22

define constipation

Answer 22

• symptom not disease - passage of hard stools less frequently than the patients normal pattern

Question 23

epidemiology of constipation

Answer 23

1/7 adults, 1/5 oaps, 1/3 children more common in women

Question 24

aetiology of constipation

Answer 24

dietpoor bowel habits medications laxative abuse IBS intestinal obstruction thyroid function travel pregnancy immobility

Question 25

constipation symptoms

Answer 25

difficulty opening bowels <3 weekhard on >25% straining on >25%

Question 26

when is constipation considered chronic

Answer 26

> 12 weeks in 6 months

Question 27

symptoms of constipation in children

Answer 27

• infrequent - foul smelling - flatulence - abdominal pain - soiling

Question 28

red flags in constipation

Answer 28

pain of defecation >40 sudden change and no cause >14 days fatigue blood repeated laxative failure or abuse

Question 29

how to treat constipation in pregnancy

Answer 29

1. bulk forming 2. add/switch osmotic 3. stimulant - prescribed only! - early labour 4. glycerol suppos

Question 30

how to treat constipation in breast feeding

Answer 30

1. bulk forming 2. add/switch osmotic 3. stimulant - short course 4. glycerol suppos

Question 31

how to treat constipation in children

Answer 31

1. behavioural and osmotic 2. add/swap stimulant 3. add softener

Question 32

how to treat acute constipation (<4 weeks)

Answer 32

1. lifestyle 2. bulk forming (3-4 days)3. osmotic (3-4 days)4. stimulant - Gradually reduce and stop after producing a soft formed stool without straining at least 3 times a week

Question 33

how to treat chronic constipation (>4 weeks)

Answer 33

1. lifestyle 2. bulk forming (3-4 days)3. osmotic (3-4 days)4. stimulant 5. prucaprolide

Question 34

how to treat faecal loading

Answer 34

• hard stools1. high dose macrogol 24 hrs 2. stimulant 12 hrs 3. glycerol/bisacodyl suppos 4. sodium phosphate/arachis oil enema - soft stools 1. stimulant 2. Docusate sodium or sodium citrate mini enema

Question 35

how to treat opioid induced constipation

Answer 35

1. osmotic plus stimulant 2. naloxegol (pamora) 3. methylnaltrexone (pamora) 4. naldemedine (pamora)

Question 36

how to treat constipation with a stoma

Answer 36

• diet and meds review - increased fluid and fibre - consider ispaghula husk (NOT in ileostomy patients as increases water and salt loss)