2.4 Pharmacology of Constipation Flashcards
What receptors can dopamine act on?
D1 to D5 in the CNS and periphery
What receptors do noradrenaline and adrenaline act on?
Adrenoceptor
What receptors fo 5-HT act on?
5-HT 1- 5HT-7 (which then can spit into differnt subtypes)
How would you change motility of the GI Tract to reduce bloating and N&V?
Increase gastrict emptying
How would you change motility of the GI Tract to reduce constipation?
Increase lower GI motility
How would you change motility of the GI Tract to reduce diarrhoea?
Decrease lower GI motility
How would you change motility of the GI Tract to reduce Irritable bowel syndrome ?
Reduce GIT spasm to reduce pain
What compounds increase motility o the GI Tract (for constipation)?
Purgatives Increase transit of food through GIT e.g. laxatrives faecal softeners Stimulant purgatives
Give examples of osmotic laxatives and how do they work?
Lactulose (raises fluid volume osmotically)
Macrogols (sequester fluid in bowel)
Magnesium sulphate and magnesium hydroxide (remain in lumen and retain water)
Give examples of faecal softeners
Docusate sodium
Liquid paraffin, arachis oil
Detergent- soften stools and ease defections
Give examples of stimulant laxatives
senna extracts, bisacodyl dantron
More for use when required rather than regular use. should be taken at night to preduce effects the next morning
What can be administered for chronic constipation in adults when other laxatives have failed? and how do they work pharamcologically?
Prucalopride
Selective seretonin 5-HT4 receptor agonist
What can be given to people who have previously been treated with 2 different types of laxatives at the highest possible recommended dose, for at least 6 months, but these havent worked well enough? and when should the medicine be reviewed ?
Lubiprostine (Cl- channel activator)
Increases intestinal fluid secretion
Patient should be reviewed after 2 weeks
What should be given to patients with IBS with constipation?
Linaclotide (guanylate cyclase-C receptor agonist)
A peptide that acts of epithjelial cells
Increases intestinal fluid secretion and transit
GI selective -not absorbed
What shoulld you advice a parient who has constapation (one off)
Advice dietary fibre, adequate fluid intake and exercise
If inaffective then:
Bulk-forming laxative (+fluid intake)
Add or sswitch to osmotic laxative
Add a stimulant laxative
If this is inaffective give lubipostone or prucalopride
