Improving gastro-intestinal motility Flashcards
What are the 4 anti-diarrhoeal drugs that can control GI motility?
- Opiods
- Anticholinergics
- Adsorbents
- Aminosalicyclates
In general how to anti-diarrhoeal drugs work?
Inhibiting muscarinic receptors, decreasing motility.
Describe the mechanism of action of anticholinergics
Decrease peristalsis by blocking binding of ACh
What are the main uses of anticholinergics?
Antispasmodic
Describe the mechanism of action of opiods
- Inhibit ACh release in myenteric plexus
- Presynaptic opiod receptors inhibit release of ACh
What are the main uses of opiods?
Symptomatic therapy of acute diarrhoea
Describe the mechanism of action of adsorbents
- Adsorb toxins
- Provides a protective coating on inflamed mucosa
What are the main uses of adsorbents?
Symptomatic therapy of acute diarrhoea
What is the problem with using adsorbents?
Absorbs water but won’t have an effect on the duration of the condition and won’t reduce water loss.
Describe the mechanism of action of aminosalicyclates
- Cleaved in the bowl by bacteria to sulfapyridine and 5-aminosalicyclic acid
- Have inflammatory effect and inhibit PG synthesis
- Have no effect on upper GIT, only become active once in the colon
What are the main uses of aminosalicyclates?
Chronic IBD and cholitis –> used for conditions affecting colon.
What can be used to increase GI motility?
Laxatives, cathartics
What are the 4 effects cathartics can have?
- Lubricant - softens faeces
- Bulk - hydrophilic colloids absorb water and increase bulk, stimulates peristalsis
- Osmotic - retain water in intestinal lumen
- Stimulant - stimulates intestinal motility via irritant effect to promote organised persitaltic action
Give examples of drugs which display the effects of cathartics
- Lubricant - mineral oil, liquid paraffin
- Bulk - methylcellulose, agar, wheat bran
- Osmotic - magnesium sulfate, polyethylene glycol, lactulose
- Stimulant - bisacodyl, phenolphthalein
