Pharmacology of the large intestine Flashcards
What are the bulk laxative medications?
Methylcellulose
Ispaghula husk
What are the osmotic laxative medications?
Magnesium sulphate
Macrogol
Lactulose
What are the faecal softener medications?
Docusate
Arachis oil
What are the stimulant purgative medications?
Bisacodyl
Senna
Which medication is an opioid anti-motility agent used to treat diarrhoea?
Loperamide
What type of molecule are bulk laxatives?
Polysaccharide polymers
Which type of laxative is first choice for common constipation?
Bulk laxatives
What is the time of action for bulk laxatives?
1 - 3 days
Which type of laxative is used for rapid preparation before an endoscopy?
Osmotic laxative (saline laxatives) - magnesium sulphate
Lactulose is made of which 2 monosaccharides?
Fructose
Galactose
Lactulose is broken down into fructose and galactose by intestinal bacteria.
They are then broken down into which 2 substances which act as osmotic agents?
Lactic acid
Acetic acid
Which type of laxative is recommended for haemorrhoids?
Faecal softeners
What is the mechanism of administration of bisacodyl?
Suppository
What is the active component of senna?
Anthracene
How does anthracene in senna increase intestinal motility?
Acts directs on the myenteric plexus to stimulate contractions
Chronic use of stimulant laxatives can lead to which condition?
Cathartic colon
What are the 4 types of diarrhoea?
Secretory
Osmotic
Motility-related
Inflammatory
What type of diarrhoea is seen in cholera?
Secretory diarrhoea
What type of diarrhoea is seen in coeliac disease?
Osmotic diarrhoea
What type of diarrhoea is seen in diabetic neuropathy?
Motility-related diarrhoea
What type of diarrhoea is seen in Crohn’s disease?
Inflammatory diarrhoea
Describe the effect of loperamide on the proximal and distal colon.
Increases activity of the proximal colon (haustral contractions) to absorb more water
Decreases activity of distal colon (mass movements) to reduce frequency of defecation
