Laxative And Diarrhoeals

Question 1

Purpose of laxatives?

Answer 1

Constipation treatment

Question 2

How is constipation caused?

Answer 2

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

Question 3

PK of laxatives

Answer 3

Orally

-but stimulant laxatives are available as suppositories or enemas

Question 4

S/E of laxatives

Answer 4

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

Question 5

Types of laxatives

Answer 5

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

Question 6

Lactulose is what type of laxative and how does it work

Answer 6

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

Question 7

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

Answer 7

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

Question 8

Safest and most generally administrated laxative?

Answer 8

Bulk laxatives

Question 9

Emollient laxative can cause what unwanted effect

Answer 9

Anal Seepage and irritation

Question 10

Example of stimulant laxatives

Answer 10

Senna, cascara

Question 11

Properties of stimulant laxatives

Answer 11

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

Question 12

Parasympathomimetics effects

Answer 12

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

Question 13

What type of laxatives are muscarinic agonists and AChE inhibitors

Answer 13

Parasympathomimetics

Question 14

Types of antidiarrhoeal drugs

Answer 14

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

Question 15

How does salt and fluid replacement work ?

Answer 15

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

Question 16

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

Answer 16

In diverticular dieases

Question 17

Loperamide

Answer 17

Anti-motility drug

Question 18

How does loperamide work

Answer 18

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

Question 19

Anti-pasmodics are used to

Answer 19

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