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Phase II - Clinical Pharmacology and Therapeutics > GI - Constipation > Flashcards

Flashcards in GI - Constipation Deck (19)
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1

Give an example of a bulk laxative.

Fybogel.

2

What is the mechanism of action of bulk laxatives?

Form gels in large intestine --> intestinal distension --> increased peristalsis.

3

What is the main side effect of bulk laxatives?

Flatulence.

4

What are the contraindications
and risks for bulk laxatives?

Adhesions, ulceration, immobile patients as risk of intestinal obstruction.

5

Give an example of a bulk forming agent.

Ispaghula husk.

6

What is the mechanism of action of bulk forming agents?

Increase faecal mass so distend the gut and increase peristalsis.

7

What are the contraindications of bulk forming agents?

Colonic atony, faecal impaction, intestinal obstruction, reduced gut motility.

8

Give an example of a stool softener.

Glycerol, arachis oil.

9

What is the mechanism of action of stool softeners?

Lubricate and soften the stool, glycerol also stimulates the gut.

10

What can stool softeners be used for?

Adhesions and ulcerations as no risk of obstruction.

11

Give an example of an osmotic laxative.

Lactulose, macrogols, phosphate enemas.

12

What is the mechanism of action of osmotic laxatives?

Nonabsorbable salts that hold water by osmosis so distend the bowel and increase intestinal activity, producing defecation in a few hours.

13

What is the caution with osmotic laxatives?

Intestinal obstruction.

14

What is another use of osmotic laxatives?

Liver failure to reduce ammonia production.

15

Give an example of an irritant/stimulant laxative.

Senna, bisacodyl, danthron, castor oil.

16

What is the mechanism of action of bisacodyl?

Acts directly on nerve fibres of mucosa of colon.

17

What is the mechanism of action of castor oil?

Broken down in small intestine to irritant chemical that irritates stomach --> peristalsis.

18

What is the risk of repeated use of irritant/stimulant laxative use?

Colonic atony, hypokalaemia.

19

Why should castor oil be avoided in pregnant women?

It can stimulate uterine contractions.