Constipation

Question 1

Bulk-forming laxatives names?

Answer 1

Plant fibers - Psyllium, Methylcellulose
Synthetic fibres - Polycarbophil

Question 2

MOA of bulk forming laxatives?

Answer 2

`1. Indigestible, hydrophilic colloids (fiber)
2. Absorb water and form bulk, emollient gel that distends colon, increasing stool mass
3. Promote peristalsis

Question 3

ADR of Psyllium and methylcellulose?

Answer 3

1. Bacterial ingestion of plant fibers within colon can cause flatus, bloating and abdominal pain
2. Interaction with absorption of other drugs. Do not take other drugs within 2-4 hours of taking Bulk-forming laxatives

Question 4

ADR of Polycarbophil?

Answer 4

Interaction with absorption of other drugs. Do not take other drugs within 2-4 hours of taking Bulk-forming laxatives

Question 5

Stool softener names?

Answer 5

Ducosate
Glycerin
Mineral oil

Question 6

Mechanism of ducosate?

Answer 6

1. Anionic surfactant that lowers surface tension of stool
2. Stool absorbs more water in gut
3. Allows mixing of aqueous and fatty substances
4. Softer stool and easier defecation

Question 7

Mechanism of glycerin?

Answer 7

Act as hydroscopic agent and lubricant, producing bowel movement in an hr

Question 8

Mechanism of mineral oil

Answer 8

1. Indigestible aliphatic hydrocarbons
2. Lubricate fecal material, retarding water absorption from stool

Question 9

Uses of stool softener?

Answer 9

“Useful where straining bowel movement to pass motion should be avoided
e.g. patients recovering from surgery or after heart attack”

Mineral oil for kids or debilitated adults to prevent and treat fecal impaction

Question 10

Names of osmotic laxatives?

Answer 10

Sorbitol, Lactulose
MgOH, Magnesium nitrate, NaPO4
Balanced PEG

Question 11

MOA of osmotic laxatives?

Answer 11

1. Osmotically-mediated water movement into bowel increases stool liquidity and volume
2. Higher volume stimulates peristalsis

Question 12

ADR of Osmotic laxative?

Answer 12

1. Diarrhoea, bloating, wind, abdominal cramps
2. Important to maintain adequate hydration

Question 13

Stimulant Laxative names?

Answer 13

Aloe
Bisacodyl

Question 14

MOA of stimulant laxative?

Answer 14

1. Produce migrating colonic contractions
2. MOA unknown but may include: direct stimulation of ENS + colonic electrolyte and fluid secretion

Question 15

Uses of stimulant laxatives?

Answer 15

Aloe rectally produce bowel movement in 2hrs
Bisacodyl rectally can produce bowel movement in 0.5h - 1hr

Question 16

What produces brown pigmentation of colon in chronic use?

Answer 16

Aloe

Question 17

What are used for colonic cleansing before colonoscopy?

Answer 17

Bisacodyl and PEG

Question 18

Chloride channel activator names?

Answer 18

Lubiprostone

Question 19

Opioid receptor antagonist name?

Answer 19

methylnaltrexone

Question 20

Serotonin 5-HT4 receptor agonist name?

Answer 20

Prucalopride

Question 21

Use of lubiprostone?

Answer 21

1. For irritable bowel syndrome
2. To treat chronic idiopathic constipation
3. Treat constipation due to opioid meds in people with current pain from other conditions.

Question 22

What are the drugs for chronic constipation?

Answer 22

Lubiprostone
Methylnaltrexone
Prucalopride

Question 23

Uses of osmotic laxative?

Answer 23

High doses can produce purgation within 1-3hrs