Constipation

Question 1

What is constipation?

Answer 1

Constipation:
- Deviates from the norm for the individual
- • The infrequent and/or unsatisfactory defecation of fewer than 3 times per week.
- usually affects colon
• Passing hard stools
• Straining,
• incomplete or painful defecation.

Question 2

How many days does it take to get faecal matter through the colon?

Answer 2

Takes 1-2 days to get faecal matter through the colon

Question 3

What is the function of the colon?

Answer 3

Function of colon
• Absorb water and electrolytes (ascending colon)
• Slow faecal passage into right colon
• Propulsion of faeces to sigmoid colon •
Storage
• Defecation

Question 4

Why is constipation common in the elderly?

Answer 4

Constipation is common in the elderly:
- physiological changes in gut that happens with ageing
- reduced acid in stomach
- immobility
- loss of neurons in gut
- could be diet related
- due to medications

Question 5

Which treatments are there for constipation?

Answer 5

Constipation treatments:
- Laxatives: stimulates peristalsis and soften bowel contents
- Bulk laxatives
- Osmotic laxatives
- Irritant laxatives= purgatives
- Lubricants and stool softeners

Question 6

What are the risk factors for constipation?

Answer 6

Constipation risk factors:
- Reported by 5-30% of population
• More common in Females > males
• Age (occurs commonly in the elderly).
- Disease: multiple sclerosis, Parkinson’s disease
- Medicines: NSAID, Antacids (aluminium)
- Medicines: Prescription: Analgesics (opiates)

Question 7

How is constipation managed?

Answer 7

Constipation management/Treatment:
-Diet (increase fibre)
• Life changes
• Laxatives (avoid dependency)
• Prokinetic drugs

Question 8

Bulk forming laxatives

Answer 8

Bulk forming laxatives
- Plant derived compounds: methyl cellulose, bran, vegetable fibres, psyllium husk
Mechanism: increase faecal bulk which stimulates peristalsis
- Safest agents which are suitable for long term use

Question 9

Osmotic laxatives

Answer 9

Osmotic laxatives
- Mimic osmotic diarrhoea : exert osmotic pressure in gut, stretches gut wall which stimulates peristalsis
- Keeps water in the bowel (water is the active ingredient in osmotic laxatives)
- Partially soluble but NOT absorbable
- Begins to work in 1-3 hours

Examples: Magnesium salts, lactulose, macrogol 3350

Question 10

Stimulant Laxatives (purgatives).

Answer 10

Stimulant Laxatives (purgatives).
- For short term use
- Activate peristaltic mechanism
- Can cause gut dependence that makes gut lazy
- Likely to be given with tramadol or codeine (anti motility effects)

1. Senna (sennoside)
   -Metabolised in gut, acts as irritant on intestinal wall  Weaker laxative than bisacodyl
   - Stimulates enteric neurons
2. Bisacodyl
   - Suppository (up the anus)- stimulates rectal mucosa: effective in 30-60 minutes
   - Oral administration: effective in 10-12 hours
3. Sodium pico sulfate
   - Oral use, metabolised in colon, stimulates mucosa

Question 11

Lubricants and stool softeners

Answer 11

Lubricants and stool softeners

-Dioctyl sodium sulfosuccinate (docusate sodium)
– detergent action, lowers surface tension, breaks up
stools, stimulates fluid accumulation, may be
combined with stimulant laxatives
• Glycerol suppository : stimulates colonic activity

Question 12

Laxatives:
Osmotic laxatives
Faecal softeners
Stimulants
Fibre

Answer 12

Laxatives:
Osmotic laxatives: increases fluid content of stool
Faecal softeners: lubricates the stool
Stimulants: increases peristalsis
Fibre: Increases stool bulk

Question 13

What is used to treat opioid induced constipation?

Answer 13

Methylnaltrexone is used to treat opioid induced constipation
- Methylnaltrexone:
- Antagonist: blocks opioid drugs peripherally
 Improves bowel function in opioid treated patients  No reduction in central effects of opioids on pain relief, because drug cannot cross BBB

Question 14

Laxatives prior to surgery/screening

Answer 14

Laxatives prior to surgery/screening
- Bowel cleansing preparations are used before colonic surgery, colonoscopy or radiology examination
- To ensure bowel is free of solids
- Not used to treat constipation

Examples:
- Moviprep: Macrogol 3350
Macrogol 3350 plus compounds such as sodium sulfate, potassium
chloride
 Bisocodyl can also be used as bowel cleaning as can sodium picosulfate
 Senna can also be added to regimen to improve efficacy of treatment
• Efficacy depends on patient compliance!!! Poor efficacy eliminates ability to use colonscopy effectively

Question 15

Which drug type is a common cause of constipation?

Answer 15

Use of analgesics/opioids can contribute to constipation formation