Constipation And Diarrhoeal Drugs Flashcards
Lifestyle managment of constipation
- healthy diet - fibre
- increase fluid intake
- increased physical activity
- toilet routine + correct positioning
Examples of bulk forming laxatives
Methyl cellulose
Isphagula husk
What is the mechanism of action of bulk forming laxatives?
Examples
- They are polysaccharide polymers that are not digested in upper GI tract
- This forms a bulky hydrated mass in gut lumen > promotes peristalsis + improving faecal consistency
methylcellulose + isphagula husk
Examples of faecal softeners
Docusate sodium
Arachis oil enema
Liquid paraffin
What is the mechanism of action of faecal softeners?
Examples
Produces softer faeces + weak stimulant laxative
docusate sodium, arachis oil enema + liquid paraffin
Examples of osmotic laxatives
Lactulose
Macrogol
What is the mechanism of action of osmotic laxatives?
Examples
- Poorly absorbed in gut
- Draw water into the colon > softens stool + stimulates bowel movements
- lactulose: semisynthetic disaccharide of fructose + galactose
- macrogol: inert ethylene glycol polymer
Examples of stimulant laxatives
Bisacodyl
Sodium picosulfate
Senna
Glycerol suppositories
What can cause diarrhoea?
- infections e.g. cholera
- radiotherapy
- anxiety
- drugs e.g. Domperidone, metoclopramide, naloxegol
Treatment of diarrhoea
- treat complication: oral rehydration or IV fluids
- treat the cause
- reduce bowel motility or increase transit time
What is the mechanism of action of opioids as anti-diarrhoeal?
Act on μ (mu) and δ (delta) receptors to slow moment in GI tract by reducing muscular contractions > allows more time for water absorption
What are adverse drug reactions of opioids
- constipation
- paralytic ileus
- N+V
- respiratory distress
- addiction
What is the mechanism of action of loperamide?
- Specific to μ and receptors in myenteric plexus
- decreases tone of longitudinal + circular smooth muscle
- reduced peristalsis + increased segmental contractions
- decreased colonic mass movement by suppressing gastrocolicreflex
What are the adverse drug reactions of loperamide?
Headache
Nausea
Drowsiness + dizziness
Dry mouth
What is the mechanism of action of stimulant laxatives?
Examples
Enhances gut motility
Increase water + electrolyte transfer into lower gut
bisacodyl, sodium picosulfate, senna, glycerol suppositories
