Constipation, Diarrhoea and Pancreatic Insufficiency

Question 1

What are the causes of constipation.

Answer 1

Dietary (inadequate calorie / fibre intake), medical conditions (colon cancer), drug (opioids, 5-HT3 receptor antagonist, calcium channel blockers), pelvic floor dysfunction

Question 2

What are some non-pharmacological measures to treat constipation

Answer 2

• Increase fluid intake
• Increase fibre intake
• Physical exercise

Question 3

How do osmotic laxatives work? Give examples.

Answer 3

Osmotic laxatives increase the water content of stools by having insoluble things in the colon, drawing water into it.

Examples:

• Polyethylene glycol (PEG) (Movicol)
• Magnesium citrate (Espon salts)

Question 4

What are the routes of administration for constipation medications.

Answer 4

• Oral (takes time to reach the distal colon)
• Suppositories (direct access to rectum)
• Enemas (access to rectum and distal sigmoid)

Question 5

How do stimulants assist in constipation?

Give two examples

Answer 5

Stimulants assist by encouraging bowel motility.

Examples:

• Senna: Prodrug, converted into sennosides which encourage bowel motility
  
  • Docusate sodium AKA colyxyl: often combined with senna

Question 6

How do 5-HT4 receptor agonists function?

Give an example:

Answer 6

Prucalopride - stimulates colonic movements to provide propulsive force for defecation.

Question 7

How do opioid antagonists work?

Give an example

Answer 7

Methylnaltrexone - used for opioid induced constipation.

Doesn’t cross the BBB, so it reduces opioid induced constipation in the bowel with impacting opioid function in the CNS

Question 8

How do guanylate cyclase-C receptor agonists work?

Give an example.

Answer 8

Linaclotide - stimulates fluid secretion and transit in the intestine

Question 9

Diarrhoea can have acute and chronic causes. Give examples for both.

Answer 9

Acute - mostly infection (viral)

Chronic: Malabsorption, IBD, medications (antibiotics, laxatives)

Question 10

How are bulking agents used to treat diarrhoea?

Answer 10

Bulking agents can be plant fibre, methylcellulose - insoluble compounds that are used to increase solidarity of stool.

Question 11

How do μ-opioid receptor agonists function?

Give two examples.

Answer 11

Opioid ANTAgonists are used to treat constipation. On the flipside, opioid agonists are used to treat diarrhoea by REDUCING gut motility.

Examples: Loperamide, Diphenoxylate

Question 12

What does cholestyramine do?

Answer 12

Cholestyramine binds to bile acids, blocking them from reabsorption and leading to excretion. Used to treat diarrhoea. Used in IBD

Question 13

How might you treat exocrine pancreatic insufficiency?

Answer 13

EPI is a digestive enzyme insufficiency due to pancreatic dysfunction.

Treatment involves replacing the missing enzymes: Creon or Panzytrat