Gastrointestinal Ulcers Flashcards

1
Q

What roles does the gastric mucosa play in the GI tract?

A

protects the cells of the stomach from the acid and enzymes in the lumen of the stomach

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2
Q

what type of cell secretes mucosa?

A

mucosal epithelial cells

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3
Q

what cells are responsible for acid secretion?

A

parietal cells

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4
Q

what is the role of HCl in the stomach?

A

to kill bacteria, viruses, and other parasites

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5
Q

what can occur if there is an overproduction of HCl?

A

overwhelm the mucous layer and buffer systems, and lead to ulcers

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6
Q

how do antacids work?

A

take NaHCO3 for example, it dissociates into Na+

the bicarbonate ion is absorbed into the blood and slightly increases the pH, which elevates the pH of the stomach

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7
Q

what are some pros and cons to using antacids?

A

pro: quick, easy, and effective in the short term to reduce stomach acid the pt is currently experiencing
cons:
- alkalotic urine can increase the deposition of calcium and phosphate to form a kidney stone
- increases blood sodium, exacerbating hypertension
- acid rebound due to feedback regulation (pump more acid out in response to antacid directly increasing pH)

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8
Q

what are the two categories of antacids? what is the difference?

A

systemic - NaHCO3
non-systemic - CaCO3, Al(OH)3, Mg(OH)2

non-systemic antacids do not effect extracellular or blood pH

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9
Q

what is the concern regarding antacids that contain Al and Ca? how is this dealt with?

A

constipating effect

give with magnesium

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10
Q

what do anticholinergics do in the treatment of overproduction of acid?

A

muscarinic Ach receptors in parietal cells stimulate HCl secretion from these cells; inhibition of these receptors reduces acid secretion, but not by much

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11
Q

how much do anticholinergics decrease acid secretion? (in percentage)

A

up to 40%

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12
Q

what are some side effects to anticholinergics?

A

dry mouth
vision problems
sedation, etc.

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13
Q

what are cytoprotectives? give two examples

A

drugs which protect cells from acidic damage, either directly or through stimulation of mucus
ex: sucralfate, misoprostol

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14
Q

how does sucralfate work?

A

it is an aluminum based salt that binds to hydrogen ions to form a gooey paste, increasing pH
also binds to degenerative cells, forming a protective layer
aka artificial mucous
works for 8-12h, specifically protects damaged tissue as well as reducing acidity

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15
Q

how does misoprostol work?

A

prostaglandin analogue

stimulates production of mucosal barrier

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16
Q

why do NSAIDs cause stomach problems?

A

COX inhibition causes PGE inhibition, and PGE is critical for mucous production in the stomach

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17
Q

how does histamine H2 blockers work?

A

inhibition of H2 receptors (receptors on parietal cells that increase HCl production)
highly effective in a number of acid-related disorders

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18
Q

what is the benefit to using H2 blockers?

A

very specific to the organ, so there are no adverse effects on the mucosa

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19
Q

name 3 H2 blockers

A

cimetidine
ranitidine
famotidine

20
Q

by what percentage does cimetidine decrease stomach acid?

A

50-60%

21
Q

what are some side effects of cimetidine?

A

gynecomastia
reduced libido
impotence
all due to binding to androgen receptors

22
Q

by what percentage does ranitidine decrease stomach acid?

A

65-70%

23
Q

what is the benefit of using ranitidine over cimetidine?

A

does not bind to androgen receptor so no SE’s relating to that

24
Q

by what percentage does famotidine decrease stomach acid?

A

75%

25
Q

why is famotidine the H2 blocker of choice?

A

most effective at reducing acid secretion and has the best safety profile (very few SE’s)
works better at higher pH so given with antacid

26
Q

what do PPIs do?

A

inhibit gastric H/K ATPase proton pump responsible for pumping the H and Cl ions into the stomach
PPIS enter the secretory canaliculus of parietal cell which opens when acid secretion occurs
pro-drug is then converted to active drug
PPIs bind very tightly to the channel, thus have a long half life

27
Q

by what percentage do PPIs decrease stomach acid?

A

90%

28
Q

give some examples of PPIs

A

omeprazole
esomeprazole
pantoprazole
rabeprazole

29
Q

when are PPIs indiciated?

A

good for GERD

other acid-dependent disorders

30
Q

what additional benefit does rabeprazole have?

A

increases mucous secretion

31
Q

how does H. pylori cause an ulcer?

A

resides in stomach, wants to escape gastric acid, so it burrows into gastric mucosa
produces urease, the enzyme that converts urea to ammonia and CO2 (CO2 causes lots of burping)
this kills mucosal epithelial cells, leaving the gut unprotected

32
Q

what are the different tests available for testing for H pylori?
which is the most popular?

A

breath test for urea and ammonia - popular
serological - from stomach
culture - from stomach
histology - stool sample

33
Q

what is the first therapy option for H pylori infection?

A

triple therapy
PPI (control acid)
2 effective antibiotics to kill the HP

34
Q

what is the next therapy option for those where triple therapy did not work?

A

quadruple therapy

PPI + 2 antibiotics + bismuth salicylate (protects stomach and make it easier for drug to reach disease)

35
Q

what is GERD?

A

lower esophageal sphincter defect allows acidic contents to contact the esophageal lining

36
Q

what kind of drugs can affect the LES tone?

A

beta blockers
CCBs
nicotine

37
Q

what are some non-pharms for GERD?

A

avoid fat, caffeine, chocolate, peppermint, and alcohol

avoid large meals, especially right before bed, stop smoking

38
Q

what is diarrhea?

A

frequent liquid stool

an intestinal disorder

39
Q

what are some causes of diarrhea?

A
foods
bacteria
virus
drug SE's
laxative abuse
malabsorption syndrome
stress
bowel tumour
40
Q

what is the recommended treatment for diarrhea?

A
clear liquids (gatorade, pedialyte)
BRAT diet
41
Q

when would we not want to stop diarrhea from occurring?

A

if caused by an infection; want to get rid of toxins

42
Q

what is one class of drugs that can be used to treat diarrhea?

A

opiates - decrease intestinal motility

43
Q

what are some side effects of opiates?

A

CNS depression

constipation

44
Q

name two opiate related agents?

A

1) diphenoxylate (lomotil)

2) loperamide (imodium)

45
Q

what are some side effects to opiate-related agents?

A

drowsiness

distention

46
Q

what do adsorbents do? give some examples

A

coat the wall of the GI tract and adsorbing the bacteria or toxins causing diarrhea (substance takes in toxin)
ex) kaopectate (kaolin and pectin), pepto-bismol