Constipation& Diarrhoea Flashcards
Definition for constipation
Frequency of bowel movements less than 3 times a week
Primary -chronic constipation without known cause
Secondary- caused by a drug (diarrhoea drug loperamide?)or medical condition
Prevalence of constipation
1% of population
More common in
Women, elderly, pregnancy
Influencing factor for primary constipation
Social : low fibre diet, lack of exercise, restricted access to toilet
Physical: immobility, dehydration, postures when defecating
Psychological: anxiety, eating disorders
Organic Causes for secondary constipation
Endocrine, metabolic disease: diabetic autonomic neuropathy, hypercalcaemia
Myopathy: myotonic muscular dystrophy type 1- trouble with bowel
Neurological disease : multiple sclerosis, Parkinson’s disease, spinal cord injury
Structural abnormalities: colonic obstruction due to colorectal cancer, rectal relapse, pelvic floor dysfunction
Drug related causes:
Al antacids Iron supplements Anti Muscarinics Opioid Tricyclic antidepressant (amitriptyline) Certain antiepileptics (phenytoin) Sedating antihistamine Ca channel blockers
Untreated chronic constipation leads to …
Faecal impaction
Types of laxatives
Bulk forming e.g. Ispaghula husk (fybogel)
Stool softening e.g. Docusate Na
Osmotic eg lactulose
Stimulant eg senna, bisacodyl (ducolax)
What is Prucalopride?
A selective 5HT 4 receptor agonist
What does Prucalopride do?
Promotes motility and mucosal secretion
Reduce transient time
What’s the MOA of Prucalopride
Binds to 5HT 4 Rec on PREsynaptical cholingeneric neurons
Increase ACh release by interneurons in the myenteric, submucosal plexus
Stools easier to move as fluids around
What is the name of Cl- channel
activator?
Lubiprostone: a selective chloride channel activator
What’s lubiprostones MOA
Increase the luminal secretion of Cl-
Which links to movement of Na and water
Activates PGE2 rec 4 (EP4) in colonic epithelial cells
Increase expression of Cl- in the apical membrane
What’s the NICE guidelines about lubiprostone and Prucalopride
At least 2 different classes of laxative has failed to provide relief
After 6 months
Second line treatment
What’s the treatment for opioid induced constipation
Opioid miu rec antagonist
Naloxegol
PERIPHERAL - PEGylation limited access to BBB
Poorly absorbed by gut, rapid metab
MOA of naloxegol
Binds to opioid Rec in myenteric and submucosal plexuses
Blocks adverse action of opioid on motility/ secretion (reduction) and reabsorption (increase)
