Laxatives - Osmotic Flashcards Preview

Pharmacology - GI and nutrition > Laxatives - Osmotic > Flashcards

Flashcards in Laxatives - Osmotic Deck (10)
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1
Q

What are examples of osmotic laxatives?

A
  • Lactulose
  • Macrogel
  • Phosphate enema
2
Q

What are indications for the use of stimulant laxatives?

A
  • Constipation and faecal impaction
  • Bowel Prep prior to surgery/endoscopy
  • Hepatic encephalopathy
3
Q

What is the mechanism of action of stimulant laxatives?

A

Based on osmotically active substances which stay in gut lumen - hold water in stool maintaining volume and stimulating peristalsis.

4
Q

Why is lactulose used in hepatic encephalopathy?

A

Reduces ammonia absorption by increasing gut transit rate and acidifying the stool, which inhibits the proliferation of ammonia-producing bacteria

5
Q

What are important adverse side effects of osmotic laxatives?

A
  • Flatulence
  • Abdominal cramps
  • Nausea
  • Diarrhoea
  • Phosphate enema - local irritation and electrolyte disturbances
6
Q

When should you not use osmotic laxatives?

A
  • Intestinal obstruction - risk of perforation
  • Phosphate enema - heart failure, ascites and electrolyte disturbances
7
Q

How would you prescribe lactulose to treat constipation with impaction?

A

15mL twice daily and titrate to effect

8
Q

How many doses of phosphate enema would you prescribe per day to treat faecal impaction?

A

One per 24 hours

9
Q

What should you advise if giving stimulant laxatives?

A

Drink plenty of water

10
Q

When treating faecal impaction rectally, what would be your first line choice?

A

Glycerol suppository first, then phostphate enema