Clinical Pharmacology of Anti-Diarrhoeal, Antispasmodics and Laxatives Flashcards
disorders of inappropraite motility
diarrhoea: can be mild inconvinience or fatal. need to control fluid balance
constipation: digested food stuck in colon and can’t be excreted
irritable bowel syndrome: can have abnormalities of gut motility such as spasms
treatement of diarrhoea
antimotility drugs: opioids, oral or liquid, inhibits release of Ach to stop muscle contraction to push food out
adsorbents: methylcellulose, absorb water to increase food stability, absorb harmful microorganisms, protect intestinal mucosa
agents to modify fluid transport: bismuth subsalicylate, absorbs fluid and electrolytes in intestinal wall, reduces hypermotility
treatment of constipation
bulk forming drugs: absorb water to increase stool bulk, increases peristalsis, increasing bacterial cell mass softens faeces
osmotic laxitives: holds water in intestines by osmosis, distends bowel to increase intestinal activity
feaces softeners: directly softens stools
stimulant laxitives: taken in inactive form, activated by bacteria in colon, induces low level inflammation which stimulates peristalsis and accumulates water and electrolytes
treatment of IBS
antispasmodics- antagonise Ach in enteric plexus
side effects: dry mouth, blurred vision, arrhythmia
relax smooth muscles
prevents gramping in IBS
Gut motility
parasympathetic fibres stimulate contraction of smooth muscles for peristalsis
sympathetic fibres are inhibitory
neurones in enteric nervous system function independantly but are influenced by PNS and SNS
myenteric plexus responsible of for peristaltic movement of bowels. receives signals from central and enteric nervous systems and vagus nerve
transports signals to muscle cells
myenteric plexus located in lower oesophagus, stomach and instestines
IBS
autoimmune inflammatory disorders of large (and small) intestines
main forms: crohn’s disease, ulceratives colitis
treatment: anti-inflammatory drugs, immunosuppressive drugs, proper nutrition, surgery
