Laxative And Diarrhoeals Flashcards Preview

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Flashcards in Laxative And Diarrhoeals Deck (19):
1

Purpose of laxatives?

Constipation treatment

2

How is constipation caused?

1) drug induced - e.g. Morphine
2) not enough fibre in diet
3) where straining exacerbates other conditions - e.g. Haemorrhoids

3

PK of laxatives

Orally
-but stimulant laxatives are available as suppositories or enemas

4

S/E of laxatives

Cramps (peristalsis stimulation)
bowel perforation in patients with intestinal obstruction
Excessive use may cause hypokalaemia and further colon impairments

5

Types of laxatives

- osmotic
- bulk
- faecal softener (emollient)
- stimulant
-parasympathomimetics

6

Lactulose is what type of laxative and how does it work

Osmotic
- it is a synthetic disaccharide
- non-absorbable sugar that increases osmolality in gut
- retain fluid in bowel

- also increase faecal bulk, softens and lubricate stool

7

Bran and methylcellulose are what type of laxatives and how do they work ?

Both are bulk laxatives that increases faecal bulk thereby stimulating local reflexes (peristalsis)
Also soften hard stools but requires adequate fluid intake to prevent intestinal obstruction

8

Safest and most generally administrated laxative?

Bulk laxatives

9

Emollient laxative can cause what unwanted effect

Anal Seepage and irritation

10

Example of stimulant laxatives

Senna, cascara

11

Properties of stimulant laxatives

Irritate intestinal mucosa thereby stimulating fluid secretion and peristalsis. (Increase motility via chemoreceptor activation and myenteric nerve plexus)

Very potent and seldom required

Normally used in terminal care and to evacuate bowel pre-surgery

12

Parasympathomimetics effects

Mimic parasympathetic effects therefore stimulates peristalsis
Have simulator effects to stimulant laxatives

13

What type of laxatives are muscarinic agonists and AChE inhibitors

Parasympathomimetics

14

Types of antidiarrhoeal drugs

-anti motility
- bulk laxatives
- fluid and salt replacements
-antipasmodics

15

How does salt and fluid replacement work ?

Treats diarrhoea by retaining Na ions back into the enterocyte via SGLT1 and SGLT2 (increase cell osmolality thereby causes water retention)

16

When does bulk forming laxatives become especially useful in treating diarrhoea?

In diverticular dieases

17

Loperamide

Anti-motility drug

18

How does loperamide work

Binds to m-receptors in myenteric plexus , activate Gi protein and inhibits AC
Less cAMP therefore Decrease motility (decrease chronotropy and decrease dromotropy)

19

Anti-pasmodics are used to

Relief cramps associated with diarrhoea and other intestinal diseases
Relax smooth muscle by inhibiting parasympathetic system