GI drugs

veranellasel's version from 2015-06-28 00:21

Section 1

Question Answer
-dineH2 blockers, block histamine
are histamine blockers reversible or irreversible?reversible
what does histamine do?increases HCl secretion a lot in parietal cells
Where is histamine released from?from enterochromaffin like cell
Where does histamine act on?from ECL to parietal cell
when do we use H2 blockers?peptic ulcers, gastritis, mild esophageal reflux
cimetidine is great but has these adverse effects:inhibits p450
blocks androgen receptors
(gynecomastia, prolactin release and decreased libido and impotence in males), crosses BBB and placenta
What drug crosses BBB and placenta?warfarin (because more lipid soluble) and heparin doesn't and cimetidine
elimination of cimetidine and ranitidine?renal
cimetidine, ranitidine, famotidine, nizatidineH2 blocker
Table for 2H2 histamine channel

Section 2

Question Answer
Proton pump inhibitorsend in prazole
best drug to stop gastric ulcersmost powerful: proton pump inhibitors
prazoleproton pump inhibitors
MOA of PPIirreversibly inhibit H/K+ ATPase on stomach parietal cells
Why are PPIs the best way to treat gastric ulcers?they stop acid secretion regardless of histamine ACH and gastrin stimulation
Do PPI bind reversibly or irreversibly to targets?irreversibly
toxicity of PPIsincreased risk of C. Diff and pneumonia, see hip fractures and decreased Mg2+ w/ longterm use

Section 3

Question Answer
Bismuth, sucraflatebinds to ulcer base and provides physical protection
allows HCO3- secretion to restablish pH
bandage for ulcerbismuth and sucrafate (peptiobismo)
When do we use bismuth and sucrafateulcer healing and traveler's diarrhea
misoprostolPGE1 analog
Misoprostol MOAincreases secretion of gastric mucous barrier and decrease acid production by mimicking PGE1
Wheredoes PGE act upon?on gastric parietal cell
When do we use misoprostol?to keep a patent ductus arteriosus (PDA) and prevent NSAID uclers and induce labor
Side effects of misoprostol?diarrhea and pregnant women can get spontaneous abortions
Why do we not give misoprostol to pregnant women?PGE1 can increase uterine tone and cause abortions

Section 4

Question Answer
Octeotidelong acting somatostatin analog
when do we use octeotide?acute variceal bleeds, acromegly, VIPoma, carcinoid tumors
Side effects of Octeotide?Nausea, cramps, steatorrhea
aluminum hydroxideantacid to neutralize acid
calcium carbonateantacid to neutralize stomach acid
why do we like antacidsthey're fast
magnesium hydroxideantacid


Question Answer
Must Go to the bathroommagnesium hydroxide side effect (diarrhea)
Aluminium hydroxide side effects:constipation,
low phosphate,
proximal muscle weakness,
which antacid can cause muscle weakness and seizures?aluminium hydroxide
aluminium?minimum amount of feces; aluminium hydroxide causes constipation
calcium carbonate?hypercalcemia, rebound acid
Why do we see rebound acid w/ Calcium carbonate?High Ca stimulates G cell to secrete gastrin
Which antacid can chelate and decrease effectiveness of other drugs?calcium carbonate


Question Answer
magnesium hydroxideosmotic laxative
magnesium citrateosmotic laxative
polyethylene glycolosmotic laxative
lactuloseosmotic laxative; used for hepatic encephalopathy by acidifying the GI contents to keep ammonia present
When do we use osmotic laxatives?constipation
Side effects of Osmotic laxatives?diarrhea, dehydration, may be abused by bulimics


Question Answer
sulfasalazinecombo drug of sulfapyridine (antibacterial) and 5- ASA anti-inflammatory; activated by colonic bacteria
When do we use sulfasalazine?Crohn's Dx and ulcerative colitis
Toxicity of sulfasalazine?malaise, nausea, sulfonamide toxicity, reversible oligospermia


Question Answer
ondansetron MOA5HT3 antagonist; stops serotonin and it's powerful
feeling queasy? Keep ON DANCing w/ondansetron!
When do we use ondansetron?Control vomiting post surgery and chemo
Side effects of ondansetronHA (vasodilation) and constipation


Question Answer
Metoclopramide MOAD2 receptor antagonist:
blocks dopamine at chemoreceptor trigger zone in the dorsal medulla or 4th ventricle
When do we use metrclopramide?diabetic and post surgery gastroparesis and antiemetic
Side effects of metoclopamideincreased Parkinson effects,
restlessness, drowsiness, fatigue, depression,
nausea, diarrhea;
see interaction w/ diagoxin and diabetic agetns
who should not use metoclopramide?small bowel obstruction or Parkinson dx

Section 5