GUT- Pharmacological Basis for Treatment of GI Disorders Flashcards
what are areas of pharmacological importance in the GI tract
gastric acid secretion
vomiting
gut motility
bile formation and excretion
what are the effects of metoclopramide on gastric motility and emptying
inhibits pre and post synaptic dopamine receptors as well as 5-HT (serotonin) receptors
it antagonises muscarinic receptors
this action enhances release of acetylcholine causing increased LES and gastric tone, accelerating gastric emptying and transit through the gut
also antagonises the D2 receptors which exerts a relaxant effect on the GI tract
prevents vomiting, increases gastric emptying
what are some clinical uses of metoclopramide
gastrointestinal reflux
simulation of gastric motility
accelerates gastric emptying
anti-emetic effect
what are some examples of antispasmodic agents
propantheline, dicloxerine, mebeverine
what is the purpose of antispasmodic agents
decrease spasm in bowel, relaxant action on GIT (relax smooth muscle in GIT)
mechanism of action of antispasmodic agents
muscarinic receptor antagonists - inhibit parasympathetic activity - this reduces spasms in the bowel
consequences of constipation
headache loss of appetite nausea abdominal distention and stomach pain holding of faecal matter = increase in water loss and drier faeces which is more painful and difficult to defecate
what are the causes of constipation
decrease of motility in the large intestine
old age
damage to enteric nervous system (may affect effect initiation of the vaso-vagal reflex)
factors which can improve the symptoms of constipation
increase fibre
laxatives
mineral oil
castor oil
treatment of constipation
purgatives - hasten food transit in the intestine
laxatives- faecal softeners and stimulants
osmotic laxatives- increase water retention in gut - increase peristalsis
what causes diarrhoea
infectious agents
toxins
anxiety
drugs
what are some therapeutic strategies to treat diarrhoea
maintain fluid and electrolyte balance
use anti-infectives
loperamide - decreases passage of faeces
codeine - decrease intestinal motility
bismuth - decreases fluid secretion in the bowel
what is the mechanism of action of loperamide
opioid receptor agonist
binds to receptor of the myenteric plexus of the large intestine and inhibits bowel function by:
controlling motility and secretion of the GIT
inhibiting gastric empyting
increasing sphincter tone
reducing muscle activity - reduces force and speed of colonic movement
does not cross BBB- no CNS effect
