GI Pharmacology

Question 1

What are the bulk laxatives? What is their uses, MOA, and cautions?

Answer 1

psyllium and methyl cellulose
MOA: non-soluble fiber or cellulose absorbs water to increase fecal mass/stool frequency
uses - constipation
cautions - flatulence, bloating, must drink large amounts of water

Question 2

What are the stimulant laxatives? What are their MOA, uses and cautions?

Answer 2

Bisacodyl, senna, cascara
MOA - directly increases colonic motility by stimulating myenteric plexus

Question 3

What are the emollient laxatives? What is it’s MOA, uses, and cautions?

Answer 3

docusate
MOA - lowers surface tension of stool and allows water to enter and softens stool

uses - constipation
cautions - abdominal cramping

Question 4

What are the osmolar laxatives? What is their MOA, uses, and cautions?

Answer 4

polyethylene glycol, lactulose, sorbitol

draws water into the colon
uses: constipation
cautions: bloating, flatulence, cramping

Question 5

What are the salt laxatives? What are their MOA, uses, and cautions?

Answer 5

MgOH, Mg Citrate
MOA - salt containing laxatives draw H2O into the colon
uses: rapid bowel prep
cautions: confusion, dizziness, irregular heart beat

do NOT use in heart/renal failure due to electrolytes

Question 6

Describe the opioid agonists. What are the MOAs, uses, and cautions?

Answer 6

loperamide - does not cross BBB
diphenoxylate - high doses can be addictive
eluxadoline - not safe without gallbladder

MOA - modulated VIP and cholinergic connection. decreases intestinal contraction/increases trait time for more water absorption

cautions - cramps, constipation, dry mouth, numbness, confusion

Question 7

What are the 5HT3 antagonists? What is its MOA, uses and cautions?

Answer 7

lotronex - ONLY TO BE USED IN WOMEN

MOA- 5HT3 agonist that slows motility and enhances fecal water reabsorption

uses - severe diarrhea

caution - contraindicated for patients with constipation, IBD stricture, diverticulitis

Question 8

Describe bismuth. What is the MOA, uses, and cautions?

Answer 8

MOA - colloidal salt that binds tons, enhances water reabsorption, and is anti-inflammatory

uses - diarrhea, reflux

cautions - black stool and tongue

Question 9

Describe octreotide. What is it’s MOA, uses and cautions?

Answer 9

MOA - synthetic somatostatin: inhibits gastric hormones
- slows GI motility
- inhibits gallbladder contraction

uses - diarrhea

cautions: contraindicated with gallstones, decreases cyclosporines, flatulence, cramps