Bulk forming laxatives

Question 1

Give the 2 main clinical indications for the use of bulk forming laxatives.

Answer 1

1) Constipation and faecal impaction, particularly in patients who cannot increase their dietary fibre intake.
2) Mild chronic diarrhoea associated with diverticular disease or IBS.

Question 2

1) What do bulk forming laxatives contain?
2) Describe the actions of these substances.
3) What is important to the action of bulk forming laxatives?

Answer 2

1) A hydrophilic substance such as a polysaccharide or cellulose which is not absorbed or broken down in the gut.
2) Attract water into the stool and increases its mass.
3) Adequate fluid intake

Question 3

1) What does an increased stool bulk cause?
2) Give the most common 2 side effects of bulk forming laxatives.
3) Give 2 rarer and more serious side effects.

Answer 3

1) stimulation of peristalsis and helps to relieve constipation.
2) Flatulence and abdominal distension.
3) Faecal impaction and GI obstruction.

Question 4

1) Give 3 groups of patients where bulk forming laxatives should not be used.
2) Name the P-drugs that are bulk forming laxatives.

Answer 4

1) Intestinal obstruction, faecal impaction, ileus.

2) bran
ispaghula husk
methylcellulose
sterculia

Question 5

1) What should bulk forming laxatives be administered with?
2) Why should bulk forming laxatives not be used for patients with new onset constipation who have recently had abdominal surgery and may be at risk of surgical ileus?

Answer 5

1) At least 300mL of water.

2) Because they will be at an increased risk of developing an intestinal obstruction.