Constipation

Question 1

Define Constipation

Answer 1

Defecation occurs less than 3 times a week

Question 2

Describe the aetiology of constipation

Answer 2

Reduced GI motility in the large colon - faecal matter stays in the colon for longer; more water reabsorption - drier stools

Question 3

Outline:
- the MOA of bulk forming laxative
- provide examples
- Onset of action

Answer 3

Increases bulk and moisture in stool which stimulates colonic activity
–> Metamucil and fybogel
–> within 24 hours

Question 4

Outline the MOA of osmotic laxatives and provide examples
- Onset of action

Answer 4

Pulls water in to expand and soften the stools making defecation easier
–> macagrol 3350 (movicol)
–> within 2 to 48 hours

Question 5

Outline the MOA of stimulant laxatives and provide examples
- Onset of action

Answer 5

irritates smooth muscle of the intestine –> induces peristalsis
- Senna, bisacodyl
- works within 6 to 12 hours

Question 6

Outline the MOA of stool softernesrs and provide examples
- Onset of action

Answer 6

Incorporates fat and water into the stool
- docusate
- Onset of action: 1 to 3 days

Question 7

Which type of laxative should not be used for opoid-induced constipation and why?

Answer 7

Bulk-forming laxative and WHY?
- Bowel obstruction and worsen faecel impaction