Constipation& Diarrhoea Flashcards
(21 cards)
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)
NICE recom on naloxegol
In opioid induced constipation patient (adult) not showing an adequate response to laxative treatment
Definition for diarrhoea
The abnormal passage of loose or liquid stools more than 3 times daily
Episodes of diarrhoea can be classified into 3 categorise…
Acute- last less than 14 days
Persistent- longer than. 14 days
Chronic- more than 4 weeks
Pathophysiology of diarrhoea
Results from excessive secretion and impaired reabsorption of fluid and electrolytes cross the intestinal epithelium
NA CL HCO3 K, glucose
What are the Cl- channels
CFTR
CLCA
Channels involved in diarrhoea mechanism
CFTR CLCA. Increase CL- excretion
NHE3- reduce NA absorption
Tight junction- increase paracellular permeability
DRA- reduced CL- absorption
Aquaporins- reduced absorption
SGLT-1 - reduce Na and glucose (–>water) absorption
