Laxatives

Question 1

Why would laxatives cause someone to want to take more laxatives?

Answer 1

Cuz overuse of laxatives can lead to constipation so the person will take more laxatives

Question 2

What might happen if you took laxatives for a long time?

Answer 2

Your body will become dependent and bowels become unresponsive to laxatives

Question 3

What are the 5 groups of laxatives?

Answer 3

1. Dietary fiber/bulk forming agents
2. Surfactant laxatives
3. Stimulant laxatives: most potent!!
4. Saline & osmotic laxatives
5. Miscellaneous

Question 4

In general how do the dietary fiber/Bulk forming agents work?

Answer 4

Not absorbed = increased delivery of H2O to LI, increase bulk, decrease sigmoid pressure –> more formed stools

Question 5

What are the bulk forming agentsthat are on the condensed drug list? There is only 1, what is its MOA?

Answer 5

Effer-syllium (Metamucil): hydrophilic muciloid that forms gelatinous mass when mixed w/ H2O

Question 6

What are Effer’s (Metamucil’s) AEs?

Answer 6

Allergic rxn, gas, obstruction, borborygmus. May inhibit coumarin (Warfarin) absorption

Question 7

Name the 2 surfactant laxatives on the CDL (condensed drug list)

Answer 7

1. Docusate sodium

2. Castor oil

Question 8

MOA/AE of Docusate sodium?

Answer 8

MOA: anionic surfactant; weakly active; stool softener; reduce the strain of defication w/ no effect on peristalsis
AE: N/V; abd pain. Can irritate intestinal mucosa, so only use for a short time

Question 9

MOA/AE of Castor oil?

Answer 9

MOA: Anionic, rapid active, effective. Produces catharsis (complete evacuation of bowels by stimulating peristalsis)
AE: colic, dehydration, electrolyte imbalance w/ overdose, uterine contraction in pregnant women

Question 10

Should’ve had this question earlier, but what is the MOA of the surfactant laxatives in general?

Answer 10

Decrease surface tension. Enable H2O and fat to be incorporated into the stool

Question 11

What is the general MOA of the stimulant laxatives?

Answer 11

MOST POTENT!! They act on the LI where they increase permeability of mucosa (leaky tight junctions) –> Na and H2O leak back into lumen. Also increase contractility by stimulating myenteric plexus. Also increase PGs and intestinal secretions

Question 12

What are the stimulant laxatives?

Answer 12

1. Diphenylmethanes; Bisacodyl

2. Anthraquinones; Senokot

Question 13

MOA of Diphenylmethanes; Bisacodyl?

Answer 13

Prodrug converted by enteric bacteria.

Question 14

AE of diphenylmethanes; Bisacodyl?

Answer 14

Overdose –> dehydration & electrolyte –> colonic inflammation

Question 15

MOA of Anthraquinones; Senokot?

Answer 15

Promote colonic motility. Natural derivative of senna. More gentle than synthetic stimulants

Question 16

AE of Anthraquinones; Senokot?

Answer 16

High doses–> abdominal pain, nephritis; increased pigment of colon mucosa, discolored urine

Question 17

What is the only Saline/Osmotic laxative on the condensed drug list?

Answer 17

Lactulose: a non-digestible sugar

Question 18

MOA of lactulose?

Answer 18

Semisynthetic disaccaride that is not absorbed. Enteric bacteria metabolize it into acids. The fecal acidification –> trapping of ammonia in stool = treatment for portal systemic encephalopathy

Question 19

What is the only IBS laxative on the CDL?

Answer 19

Lubiprostone

Question 20

MOA of lubiprostone?

Answer 20

Direct activation of Cl- channels in intestine –> increased secretion & motility