Laxatives Flashcards

1
Q

What is the MOA of bulk-forming laxatives?

A

Retaining fluids within the stool and iincreasing faecal mass, therefore stimmulating peristalsis + stool softening

E.g. Methylcellulose, Physillium jusk, Polycarbophil

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2
Q

Name examples of bulk-forming laxatives

A

Ispaghula husk
Methylcellulose,
Physillium husk
Polycarbophil

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3
Q

What are side-effects of bulk-forming laxatives

A
  • Bloating (due to fermentation)
  • Diarrhoea
  • Worsening constipation (if patient does not drink enough water or slow transit disorder or defacatory disorder)

Methylcellulose,
Physillium husk

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4
Q

What are advanatages and indications of Bulk-forming laxatives?

A
  • First line in chronic constipation after lifestyle changes

Take 2-3 days to work

Methylcellulose,
Physillium husk

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5
Q

What are the main disadvanatages and side-effects of bulk-forming laxatives?

A

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

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6
Q

What is the MOA of osmotic laxatives?

A

Increase osmotic pressure and draws water into the intestinal lumen –> stimmulation of intestinal motility (peristalsis)

E.g. Lactulose
Macrogol
polyethylene glycol

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7
Q

Name 3 examples of Osmotic Laxatives

A

Macrogol
polyethylene glycol
Lactulose

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8
Q

What are advanatages and indications of Bulk-forming laxatives?

A

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

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9
Q

What are the disadvantages and side-effects of osmotic diuretics?

A

Take 2-3 days to work

Side effects
* Diarrhoea (especially lactulose if lactose intolerant)
* Dehydration
* Flatulence, bloating
* Electrolyte abnnormalities (if magnesium salts are used)

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10
Q

What is the MOA of stimmulant laxatives?

A

Stimulation of epithelial cell secreation of electrolytes into colonic lumen

  1. increased secretion of fluid into the colon
  2. Myneteric neuronal depolarisation –> colonic contractions –> peristalsis

Senna
Bisacodyl and sodium picosulfate

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11
Q

Name some stimmulant laxatives

A

Bisacodyl and sodium picosulfate (colonic + rectal nerves)
Senna (colonic nerves)
(Docusate is emulsification with mild stimmulant activity)

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12
Q

What are the advanatages and indications for stimmulant laxatives

A

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
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13
Q

What are the side-effects of stimmulant laxatives?

A
  • Diarrhoea
  • Senna: Melanosis coli (benign hyperpigmentation of colon)
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14
Q

What is the management of opioid-associated constipation?

A

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)

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15
Q

What is the aim of laxative treatment and when should it be reduced?

A

Gradually titrate the laxative dose(s) up or down aiming to produce soft, formed stool without straining at least three times per week.

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