GI: LAXATIVES, BULK FORMING

Question 1

BULK FORMING LAXATIVES: COMMON INDICATIONS

Answer 1

• Constipation and faecal impaction

- Mild chronic diarrhoea (assoc diverticular dx or IBS)

Question 2

BULK FORMING LAXATIVES: MOA

Answer 2

• Hydrophilic substance (eg polysaccharide or cellulose) which is not absorbed or broken down in the gut
• This attracts water into the stool and increases its mass
• Adequate hydration important to assist bulk forming laxatives
• Increased stool bulk stimulates peristalsis and helps to relieve constipation
• Also assists in chronic diarrhoea

Question 3

BULK FORMING LAXATIVES: ADVERSE EFFECTS

Answer 3

• Mild abdominal distension and flatulence

- Rarely can cause faecal impaction and GI obstruction

Question 4

BULK FORMING LAXATIVES: WARNINGS

Answer 4

• Intestinal obstruction or faecal impaction

- Generally should not be used in patients with ileus

Question 5

BULK FORMING LAXATIVES: INTERACTIONS

Answer 5

• No clinically significant drugs interactions

Question 6

BULK FORMING LAXATIVES: EXAMPLES

Answer 6

• Isphaghula husk
• Methylcellulose
• Sterculla

Question 7

BULK FORMING LAXATIVES: CLINICAL TIP

Answer 7

Do not routinely use bulk-forming laxatives for patients with new-onset constipation who have recently had abdominal surgery and may have surgical (paralytic) ileus, as they will be at increased risk of developing intestinal obstruction.