Laxatives Flashcards
What is the MOA of bulk-forming laxatives?
Retaining fluids within the stool and iincreasing faecal mass, therefore stimmulating peristalsis + stool softening
E.g. Methylcellulose, Physillium jusk, Polycarbophil
Name examples of bulk-forming laxatives
Ispaghula husk
Methylcellulose,
Physillium husk
Polycarbophil
What are side-effects of bulk-forming laxatives
- Bloating (due to fermentation)
- Diarrhoea
- Worsening constipation (if patient does not drink enough water or slow transit disorder or defacatory disorder)
Methylcellulose,
Physillium husk
What are advanatages and indications of Bulk-forming laxatives?
- First line in chronic constipation after lifestyle changes
Take 2-3 days to work
Methylcellulose,
Physillium husk
What are the main disadvanatages and side-effects of bulk-forming laxatives?
Take 2-3 days to work so not for acute constipation + need to drink water with it
Worsening constipation + contraindicated if
* slow transit disorders
* defactory disorders
Other side-effects
* bloating (due to fermenntation)
* diarrhoea
*
Methylcellulose,
Physillium husk
What is the MOA of osmotic laxatives?
Increase osmotic pressure and draws water into the intestinal lumen –> stimmulation of intestinal motility (peristalsis)
E.g. Lactulose
Macrogol
polyethylene glycol
Name 3 examples of Osmotic Laxatives
Macrogol
polyethylene glycol
Lactulose
What are advanatages and indications of Bulk-forming laxatives?
2nd line in chronic constipation (or in addition to bulk forming)
(Macrogol first line, then lactulose 2nd line)
Also take 2-3 days to work
- Macrogol is licenced for used in faecal imparction
Are also used as bowel prep before Endoscopy
What are the disadvantages and side-effects of osmotic diuretics?
Take 2-3 days to work
Side effects
* Diarrhoea (especially lactulose if lactose intolerant)
* Dehydration
* Flatulence, bloating
* Electrolyte abnnormalities (if magnesium salts are used)
What is the MOA of stimmulant laxatives?
Stimulation of epithelial cell secreation of electrolytes into colonic lumen
- increased secretion of fluid into the colon
- Myneteric neuronal depolarisation –> colonic contractions –> peristalsis
Senna
Bisacodyl and sodium picosulfate
Name some stimmulant laxatives
Bisacodyl and sodium picosulfate (colonic + rectal nerves)
Senna (colonic nerves)
(Docusate is emulsification with mild stimmulant activity)
What are the advanatages and indications for stimmulant laxatives
Take 6-12 h to work
- after bulk-formin and osmotic if stools are soft but difficult to pass, or there is a sensation of inadequate emptying
- Quicker than other forms of laxatives
What are the side-effects of stimmulant laxatives?
- Diarrhoea
- Senna: Melanosis coli (benign hyperpigmentation of colon)
What is the management of opioid-associated constipation?
Do not prescribe bulk-forming laxatives.
Offer an osmotic laxative and a stimulant laxative (or docusate is an alternative which also has stool-softening properties)
What is the aim of laxative treatment and when should it be reduced?
Gradually titrate the laxative dose(s) up or down aiming to produce soft, formed stool without straining at least three times per week.
