Pharmaco Laxatives

Question 1

Laxative function

Answer 1

Stimulate intestinal peristalsis by increasing movement of bowel content
Decrease intestinal transit time
Facilitate defecation

Question 2

What are laxatives used for

Answer 2

Constipation
Evacuate bowel before surgery or diagnostic examination
Eliminate drugs or poisons from gut

Question 3

Why are laxatives abused

Answer 3

Because they cause loss of water which can lead to weight loss

Question 4

Types of laxatives based on MOA

Answer 4

Bulk forming
Stimulant
Surfactant
Osmotic

Question 5

Which type of laxative can be used long term without big side effects

Answer 5

Bulk forming

Question 6

What can happen if long term use of other laxatives like osmotic ones

Answer 6

Electrolytes depletion

Question 7

What type of laxatives could lead to dépendance

Answer 7

Osmotic and stimulant

Question 8

What are bulk forming laxatives

Answer 8

Indigestible hydrophilic substances that resembles natural dietary fiber
Polysaccharide polymer not broken down in upper GIT

Question 9

How do bulk forming laxatives act

Answer 9

They retain water in git lumen which promotes peristalsis

Question 10

Examples of bulk forming laxatives

Answer 10

Pectins
Methyl cellulose
Plants gums like sterculia, bran

Question 11

Action of stimulant laxatives

Answer 11

Act on sensory nerve endings in gut to stimulate peristalsis directly

Irritate intestinal mucosa to cause excess gut motility

Increase secretions in GIT

Question 12

Example of stimulant laxatives

Answer 12

Castor oil
Plant extract of sema
Bisacodyl (synthetic )

Question 13

Preferred mode of administration of bisacodyl

Answer 13

Suppository ( can cause irritation of rectal mucosa )

Question 14

Time of action of bisacodyl

Answer 14

15-30 mins

Question 15

Senna composition

Answer 15

Anthracene

Sugars to form glycosides

Question 16

Stimulant laxatives MOA

Answer 16

Drug passes in colon unchanged 
Bacteria hydrolyse glycosidic bond 
Free anthracene derivatives released 
Derivatives act on myenteric plexus 
Increased smooth muscle activity
Défécation

Question 17

Second name of surfactant laxatives

Answer 17

Fecal softeners

Question 18

MOA of surfactant laxatives I

Answer 18

Detergent like action
Change surface tension of fluids in bowel
Cause émulsion on bowel contents
Cause more water retention
Content becomes softer and easier to pass

Weak stimulant activity too

Question 19

Surfactant laxatives examples

Answer 19

Docusate sodium

Liquid paraffin

Question 20

Are there lot of adverse effects with surfactant laxatives ?

Answer 20

No just few

Sometimes mild GIT reactions

Question 21

Osmotic laxatives nature

Answer 21

Poorly absorbed solutes

Question 22

MOA of osmotic laxatives

Answer 22

Poorly absorbed solute increase volume of fluid in lumen of bowel by osmosis

Accelerate transfer of gut through small intestine

Large volume of gut material into colon

When material gets to colon causes distension and purgation

Question 23

Time of action of osmotic laxatives

Answer 23

1h

Question 24

Who can’t take osmotic laxatives

Answer 24

Children
Patients with poor renal function

Could cause
Heart block
NM block
CNS depression

Question 25

Type of osmotic laxatives

Answer 25

Magnesium sulfate
Magnesium hydroxide
Lactulose (semi synthetic disaccharide of fructose and galactose)

Question 26

MOA of lactulose

Answer 26

Lactulose converted in colon to poorly absorbed sugars

Fermented into colon
Lactic and acetic acids formed
Take 2-3 days to act

Question 27

Adverse effects of lactulose at high doses

Answer 27

Flatulences 
Cramps
Diarrhea
Electrolyte 
Electrolyte disturbance