Peri-op Care: Common Drugs

Question 1

Name 3 types of drug that can be used to relieve constipation. What is their MOA?

Answer 1

1. FYBOGEL: high fibre bulk producer which activates stretch receptors in the bowel and triggers peristalsis, and retains water to soften stool
2. LACTULOSE: osmotic laxative that acts by retaining fluid in the bowel, causing mild osmotic diarrhoea.
3. SENNA: stimulates peristalsis

Question 2

What are the side effects of senna? Why should it not be used long term?

Answer 2

Side effects:

• GI discomfort
• diarrhoea
• fluid and electrolyte imbalance
• haematuria
• albuminuria
• urine discolouration
• skin reactions

Should not be used long term as:
- can cause hypokalaemia

Question 3

What are the side effects of lactulose? Why should it not be used long term?

Answer 3

Side effects:

• abdominal pain
• flatulence
• nausea and vomiting
• electrolyte imbalances (uncommon)

Should not be used long term as:

• can cause dehydration
• can cause tolerance
• doesn’t address underlying issue