Gastrointestinal Pharmacology

Question 1

name the H2 blockers

Answer 1

-dine

Cimetidine

ranitidine

famotidine

nizatidine

“Take H2 blockers before you dine. Think ‘table for 2’ to remember H2.”

Question 2

H2 blockers–mechanism

Answer 2

reversible block of histamine H2 receptors –> decrease H+ secretion by parietal cells

Question 3

H2 blockers–use

Answer 3

peptic ulcer

gastritis

mild esophageal reflux

Question 4

cimetidine–toxicity

Answer 4

(H2 blocker)

potent inhibitor of cytochrome P-450

antiandrogenic effects–prolactin release, gynecomastia, impotence, dec libido in males

can cross blood brain barrier–confusion, dizziness, headaches

can cross placenta

Question 5

cimetidine and ranitidine–toxicity

Answer 5

(H2 blockers)

dec renal excretion of creatinine

Question 6

name the proton pump inhibitors

Answer 6

omeprazole

lansoprazole

esomeprazole

pantoprazole

dexlansoprazole

Question 7

proton pump inhibitors–mechanism

Answer 7

irreversibly inhibit H+/K+ ATPase in stomach parietal cells

Question 8

proton pump inhibitors–use

Answer 8

peptic ulcer

gastritis

esophageal reflux

Zollinger-Ellison syndrome

Question 9

proton pump inhibitors–toxicity

Answer 9

inc risk of C. difficile infection, pneumonia

decrease serum Mg2+ with long term use

Question 10

how does antacid usage affect other drugs?

Answer 10

affect absorption, bioavailability, or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying

Question 11

name 3 types of antacids

Answer 11

aluminum hydroxide

calcium carbonate

magnesium hydroxide

Question 12

what can all antacids cause?

Answer 12

hypokalemia

Question 13

aluminum hydroxide–toxicity

Answer 13

contipation

hypophosphatemia

proximal muscle weakness

osteodystrophy

seizures

“Aluminimum amount of feces”

Question 14

calcium carbonate–toxicity

Answer 14

hypercalcemia–milk alkali syndrome

rebound acid increases

can chelate and decrease effectiveness of other drugs (ie. tetracycline)

Question 15

magnesium hydroxide–toxicity

Answer 15

diarrhea

hyporeflexia

hypotension

cardiac arrest

“Mg2+ = Must go to the bathroom”

Question 16

bismuth, sucralfate–mechanism

Answer 16

bind to ulcer base which protects it and allows HCO3- secretion to reestablish pH gradient in the mucous layer

Question 17

bismuth, sucralfate–use

Answer 17

inc ulcer healing

travelers’ diarrhea

Question 18

misoprostol–mechanism

Answer 18

a PGE1 analog

inc production and secretion of gastric mucous barrier

dec acid production

Question 19

misoprostol–use

Answer 19

prevention of NSAID induced peptic ulcers (NSAIDs block PGE1 production)

maintenance of a patent ductus arteriosis

also used off label for induction of labor–ripens cervix

Question 20

misoprostol–toxicity

Answer 20

diarrhea

Question 21

contraindication for misoprostol

Answer 21

women of childbearing potential (abortifacient)

Question 22

octreotide–mechanism

Answer 22

long acting somatostatin analog

inhibits secretion of various splanchnic vasodilatory hormones

Question 23

octreotide–use

Answer 23

acute variceal bleeds

acromegaly

VIPoma

carcinoid tumors

Question 24

octreotide–toxicity

Answer 24

nausea

cramps

steatorrhea

inc risk of cholelithiasis due to CCK inhibition

Question 25

name the osmotic laxatives

Answer 25

magnesium hydroxide magnesium citrate polyethylene glycol lactulose

Question 26

osmotic laxatives--mechanism

Answer 26

provide osmotic load to draw water into the GI lumen

Question 27

osmotic laxatives--use

Answer 27

constipation

Question 28

lactulose--use and specific mechanism

Answer 28

(osmotic laxative) helps treat hepatic encephalopathy since gut flora degrade it into metabolites (lactic acid and acetic acid) that promote nitrogen excretion as NH4+

Question 29

osmotic laxatives--toxicity

Answer 29

diarrhea dehydration may be abused by bulimics

Question 30

sulfasalazine--mechanism

Answer 30

combination of sulfapyridine (antibacterial) and 5-aminosalicyclic acid (anti-inflammatory) activated by colonic bacteria

Question 31

sulfasalazine--use

Answer 31

ulcerative colitis Crohn disease (colitis component)

Question 32

sulfasalazine--toxicity

Answer 32

malaise nausea sulfonamide toxicity reversible oligospermia

Question 33

loperamide--mechanism

Answer 33

agonist at mu-opioid receptors slows gut motility poor CNS penetration (low addictive potential)

Question 34

loperamide--use

Answer 34

diarrhea

Question 35

loperamide--toxicity

Answer 35

constipation nausea

Question 36

ondansetron--mechanism

Answer 36

5-HT3 antagonist decrease vagal stimulation powerful central acting antiemetic

Question 37

ondansetron--use

Answer 37

control vomiting postop and in patients undergoing cancer chemotherapy "at a party but feeling queasy? Keep **on danc**ing with **ondans**etron"

Question 38

ondansetron--toxicity

Answer 38

headache constipation QT interval prolongation

Question 39

metoclopramide--mechanism

Answer 39

D2 receptor antagonist inc resting tone, contractility, LES tone, motility does not influence colon transport time

Question 40

metoclopramide--use

Answer 40

diabetic and postsurgery gastroparesis antiemetic

Question 41

metoclopramide--toxicity

Answer 41

inc Parkinsonian effects, tardive dyskinesia restlessness drowsiness fatigue depression diarrhea

Question 42

what is a possible drug interaction with metoclopramide?

Answer 42

digoxin diabetic agents

Question 43

what is a contraindication for metoclopramide?

Answer 43

patients with small bowerl obstruction or Parkison disease (due to D2 receptor blockade)

Question 44

orlistat--mechanism

Answer 44

inhibits gastric and pancreatic lipase --\> dec breakdown and absorption of dietary fats

Question 45

orlistat--use

Answer 45

weight loss

Question 46

orlistat--toxicity

Answer 46

steatorrhea dec absorption of fat soluble vitamins

Question 47

ursodiol (ursodeoxycholic acid)--mechanism

Answer 47

non toxic bile acid inc bile secretion dec cholesterol secretion and reabsorption

Question 48

ursodiol (ursodeoxycholic acid)--use

Answer 48

primary biliary cirrhosis gallstone prevention or dissolution