GI Pharmacology 2 - Slides 16-30

Question 1

MOA of laxatives?

Answer 1

Increase motility
Increase water content of stool
Decrease colonic water and NaCl absorption (keeps more water in the stool)

Question 2

Indications for laxatives?

Answer 2

Prepare bowel for surgery
Hasten bowel excretion of toxins
Post-operative stimulation
Minimize straining in CV disease pts
Relief of TEMPORARY constipation

Question 3

Contraindications for laxatives?

Answer 3

Underlying bowel disease

Question 4

Side effects of laxatives?

Answer 4

Acute: Nausea, abdominal cramps, diarrhea

Chronic (Cathartic Colon Syndrome):
Mucosal inflammation
Atrophy of outer muscle layers
Damage to nerve plexus
Malabsorption, dehydration, protein loss
Disruption of intestinal flora

Question 5

What types of laxatives are there?

Answer 5

Stimulants or irritants
Bulk forming - dietary fiber
Stool softeners
Osmotic agents

Question 6

What is castor oil?

Answer 6

A laxative (stimulant/irritant), increases motility and electrolyte secretion

Question 7

What is Senna?

Answer 7

A laxative (stimulant/irritant), increases colonic motility

Question 8

What is Bisacodyl?

Answer 8

A laxative (stimulant, irritant), increases colonic motility

Question 9

What is Phenothalin?

Answer 9

A laxative (stimulant/irritant) - was removed

Question 10

Side effects of laxatives?

Answer 10

Abdominal cramps
Diarrhea
Muscle weakness

Question 11

What type of laxative is the strongest?

Answer 11

Stimulants or irritants

Question 12

Name the bulk forming, non-digestable dietary fibers

Answer 12

Psyllium

Methylcellulose

Question 13

How should Psyllium, Methylcellulose be taken

Answer 13

Mixed with water before taking

Question 14

How do Psyllium, Methylcellulose work?

Answer 14

They increase bulk and water content of stool to increase motility
Also increased volume augments peristalsis

Question 15

Adverse effects of Psyllium, Methylcellulose?

Answer 15

Binds drug
Flatulence
Cramps

Question 16

Name the stool softeners

Answer 16

Mineral oil
Glycerin
Docusate sodium (Colase)

Question 17

How do stool softeners work?

Answer 17

They emulsify with stool to increase water content and lubricate

Question 18

Name the osmotic agents

Answer 18

Magnesium sulfate
Magnesium hydroxide
Lactulose
Mannitol

Question 19

How do osmotic agents work?

Answer 19

Increase water content

Increase motility

Question 20

What is Diphenoxylate?

Answer 20

Atropine

Ant-diarrheal agent, increases water absorption and decreases GI motility locally

Question 21

What is Difenoxin?

Answer 21

Active metabolite of diphenoxylate
Atropine
Ant-diarrheal agent, increases water absorption and decreases GI motility locally

Question 22

What is Loperimide?

Answer 22

Ant-diarrheal agent, increases water absorption and decreases GI motility locally

Question 23

Adverse effects of anti-diarrheal agents?

Answer 23

Constipation
Exaggerated GI effects
Megacolon

Question 24

What is Bismuth subsalicylate?

Answer 24

Inhibits intestinal secretions
Effective in INFECTIOUS diarrhea
Taken frequently
Worry about bismuth and salicyalate toxicity

Question 25

What is Kaopectate?

Answer 25

Anti-diarrheal agent | Now contains bismuth subsalicylate

Question 26

What is Ulcerative collitis?

Answer 26

Confluent inflammation of mucosal layer of the colon

Question 27

What is Chron's disease?

Answer 27

Transmural nonconfluent inflammation of submucosal layer near ileocecal valve leads to strictures and fistulas

Question 28

What is Mesalamine?

Answer 28

5-ASA Metabolized to 5-ASA in colon Exact mechanism unknown Inhibits TNF, IL-2, NF-KB

Question 29

Toxicities of Mesalamine?

Answer 29

Headache Dyspepsia Sulfa Headache, fatigue, allergic reactions

Question 30

What is Sulfasalazine?

Answer 30

Prodrugs for 5ASA in ulcerative collitis

Question 31

What is Olsalazine?

Answer 31

Prodrug for 5ASA in ulcerative collitis

Question 32

What is Balsalazide?

Answer 32

Prodrug for 5ASA in ulcerative collitis

Question 33

Where do Sulfasalazine and Osalazine release 5ASA?

Answer 33

In the colon

Question 34

How do dif Mesalamine preparations differ?

Answer 34

Vary in where along the GI tract 5 ASA is released Sulfasalazine and Osalazine release 5 ASA in the colon

Question 35

Other tx for IBS (Chrohn's disease)?

Answer 35

Glucocorticoids Azathioprine, 6-Mercaptopurine (severe chrohn's disease after surgery) Methotrexate Cyclosporine Infliximab (anti TNF antibody) Antibiotics (Metronidazole, ciprofloxacin, clarithromycin)