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Pharm 2 > Lecture 3 - GI Drugs > Flashcards

Lecture 3 - GI Drugs Flashcards

1
Q

What are different ways to treat PUD?

A

decrease gastric acid secretion (PPI, H2 blockers)
neutralize gastric acids (Antacids)
enhance mucosal defenses
eradicate H. Pylori (clarithromycin, amoxicillin, PPI)

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2
Q

How to H2 receptor antagonists work in PUD treatment?

A

histamine is a stimuli for acid secretion (the only stimuli present at night)
blocks the receptors on parietal cells thus blocking the stimuli for acid production

Cimetidine
Famotidine

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3
Q

ADME of H2 Receptor Antagonists

A

Cimetidine
Famotidine

specific and reversible
blunts parietal cells response to ACh and gastrin
rapidly absorbed (minium protein binding capacity)
renal elimination (decrease dose in renal insufficient pts)
can develop tolerance
cross placenta – eliminated in breast milk
drug -CYP interaction in Cimetidine (global CYP inhibitor)

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4
Q

Which drug is considered safer, cimetidine or famotidine?

A

Famotidine because it doesn’t have CYP drug drug interactions

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5
Q

What are side effects of cimetidine?

A

CYP CYP interactions

hormonal - gynecomastia, impotence

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6
Q

Omeprazole

A

PPIs
prodrug
irreversible blockade of parietal cell H+/K+ ATPase

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7
Q

When do you instruct your pt to take omeprazole?

A

30-60 minutes before breakfast

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8
Q

When are H2 receptors antagonists helpful to take?

A

at night

since there is no gastrin production at night but there is still histamine production stimulating acid production

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9
Q

Does Cimetidine cross the placenta?

A

Yes

it is an H2 receptor antagonist

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10
Q

When do you use Famotidine?

A

prophylactically before NSAID treatment
found to markedly reduce ulcer incidence

dose-dependent effect

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11
Q

What are the indications for Famotidine?

A

same as Cimetidine

PUD
GERD

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12
Q

What is the MOA of PPI?

A

prodrug

acid labile - need enteric coating to get passed stomach

weak base accumulates in parietal cell canaliculus –then protonated form of drug binds covalently to enzyme

Proton Pump is the final common pathway of ALL stimuli to acid secretion (ACh, H2, gastrin)

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13
Q

How do enzymes that were bound by PPI recover?

A

there has to be synthesis of new enzyme

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14
Q

What are the adverse effects of PPIs?

A

Nausea
Diarrhea
dizziness

long term use - PNA, infection, Carcinoma
increase risk of fractures
decrease B12 absorption
increase risk of CKD

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15
Q

ADME of PPI

A

single daily dose decreases acid secretion for 2-3 days
hepatic metabolism
crosses placenta

poor choice for occasional heartburn

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16
Q

Are all parietal cells producing acid at the same time?

A

no

cells are only expressing the H+/K+ ATPase if they are producing acid

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17
Q

What is the first line drug for Zollinger - Ellison Syndrome?

A

PPI - omeprazole

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18
Q

When is omeprazole used?

A

for PUD and GERD

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19
Q

MOA for antacids

A

neutralize acid on lumen side

weak bases are poorly absorbed
stays in lumen

Mg(OH)2
Al(OH)3

often given in combo because Mg(OH)2 causes diarrhea and Al(OH)3 causes constipation

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20
Q

When should antacids be taken?

A

postprandial
need acid in the lumen to be effective

good for occasional heartburn

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21
Q

Why is CaCO3 a less ideal antacid?

A

because it has CO2 as a side product

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22
Q

What do you tell a pt who is taking regular drugs but now needs to add in an antacid? (in regards to when to take the antacid)

A

Since antacids can alter the absorption of other drugs you need to take your other drugs 2 hours after you have taken the antacid

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23
Q

Al(OH)3 and CaCO3 decrease the absorption of which drugs?

A

tetracycline
isoniazid
ketaoconazole

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24
Q

What do you have to keep in mind when prescribing Mg(OH)2 in regards to drug absorption?

A

this antacid gets more absorbed that the others so it can cause an increase in urine pH and thus alter the elimination of salicylates and quinidine

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25
Q

Are PPIs available OTC?

A

yes

Prilosec

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26
Q

When is gastrin secreted and what does it do?

A

Gastrin is released in response to stretch of the stomach and stimulates acid production

not produced at night

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27
Q

Sucralfate

A

mucosal protective agent
sucrose + sulfated Al(OH)3

forms paste-like gel at low pH that adheres to positively epithelial cells as well as ulcer craters

must take BEFORE eating

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28
Q

What are the risk factors of PUD?

A 
presence of H. pylori 
NSAIDS
salicylates (aspirin) 
Tobacco
Heredity and age
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29
Q

When do you instruct your patients to take sucralfate?

A

BEFORE they eat

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30
Q

What must you tell your patient who are taking sucralfate in addition to other drugs as far as WHEN to take these drugs?

A

you must take sucralfate BEFORE you eat but this gel can absorb other drugs (tetracylcine, phenytoin, digoxin) so wait 2 hours before you take sucralfate

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31
Q

Which drugs can be absorbed by sucralfate?

A

tetracylcine
phenytoin
digoxin

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32
Q

Why don’t you want to coadmin antacids with sucralfate?

A

because sulcrafate needs an acidic environment to form paste and be protective

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33
Q

Is sucralfate absorbed?

A

no

34
Q

Bismuth subsalicylate

A

often added to treatment with H. Pylori –since it has antimicrobial effects

absorbed – makes stool and tongue black

binds selectively to ulcers –> protects against acid and pepsin

35
Q

Can you give bismuth subsalicylate to children?

A

no

salicylic avid –Reye’s syndrome

36
Q

What do you have to advise your pts who are going to start taking bismuth subsalicylate?

A

don’t worry if your stool or tongue turn black, that is a typical SE of the drug since it gets absorbed

37
Q

Misoprostol

A

mucosal protective agent

PG1 analog
blocks acid secretion on ECL and parietal cell via G protein

38
Q

What are the contraindications of Misoprostol?

A

Pregnancy

since its a prostaglandin analog and PGs can induce contractions

39
Q

What are different ways to decrease acid in the stomach?

A

block H2 receptors on parietal cells

enhance somatostatin release or give somatostatin analog (somatostatin blocks everything)

40
Q

What are different ways to treat ZES?

A

PPI

somataostatin analog

41
Q

What controls the vomiting center?

A

ACh

42
Q

What stimuli can cause vomiting?

A
  • motion sickness
  • pain, repulsive sights, smells, emotional factors
  • endogenous toxins, durgs
  • stimuli from pharynx and stomach
43
Q

CTZ

A

chemotrigger zone

feeds directly into vomiting center

44
Q

Where is the majority of seretonin secreted?

A

the gut

45
Q

Metoclopramide

A

anti-emetic
prokinetic

D2 receptor antagonist
5HT3 receptor antagonist
5HT4 receptor agonist
cholinergic stimulant

46
Q

How does metoclopramide work as an antiemetic?

A

acts as a prokinetic via:

  • enhances ACh release in myenteric plexus, improving intestinal smooth muscle response to ACh
  • increases esophageal sphincter tone
  • increases gastric emptying via relaxing pyloric sphincter

used for chemo drug induced N/V

47
Q

What drug is used in chemo drug induced N/V?

A

metoclopramide

48
Q

What are the adverse effects of metoclopramide?

A

dopamine D2 receptor antagonist can cause extrapyramidal (Parkinsons like) sxs and tradive dykinesia

BBW - long term use - irreversible muscle spasm (dyskinesia)

49
Q

What can occur with long term use of metoclopramide?

A

irreversible muscle spasm (dyskinesia)

50
Q

Odansatron

A

PO, IV

selective 5HT3 receptor antagonist
give PRIOR to chemotherapy or surgery
little to no effect on muscarinic or dopaminergic receptors
Adverse: constipation

51
Q

What are the side effects of odansatron?

A

constipation

52
Q

When do you give odansatron?

A

PRIOR to surgery or chemotherapy

53
Q

Besides D2 receptor antagonists and 5HT3 receptor antagonists, what are other targets for antiemetics?

A

H1 receptor antagonists
Muscarinic antagonists
Neurokinin 1 antagonists

54
Q

Types of laxative

A

fiber
lubiprostone
linaclotide
Mg(OH)2

55
Q

What are contraindications of laxatives?

A

cramps
colic
N/V
abdominal pain undx

56
Q

Lubiprostone indications

A

IBS w/ constipation

idiopathic chronic constipation

57
Q

What is the MOA for lubiprostone?

A 
ClC2 CL channel activator 
increases intestinal fluid secretion 
increases number of bowel movements 
acts luminally (minimally absorbed)
58
Q

What are the adverse effects of lubiprostone?

A

diarrhea, N, abdominal pian, distention

59
Q

What are the indications for Linaclotide?

A

IBS w. constipation

idiopathic chronic constipation

60
Q

What is the MOA of linaclotide?

A

activation of cystic fibrosis transmembrane conductance regulator (CFTR)
increase intestinal fluid secretions
increase number of bowel movements
acts luminally (minimal absorption)

61
Q

What are the adverse effects of linaclotide?

A

diarrhea

62
Q

What are the contraindications of linaclotide?

A

in peds pts d/t dehydration related deaths

63
Q

Saline laxative

A

Mg(OH)2

*if combined with Al(OH)3 –> antacid

osmotic pressure leads to accumulation of fluids in GI tract and stimulation of peristalsis

64
Q

Cathartic dose

A

Mg(OH)3
complete evacuation of bowel in 3 hours
used for colonoscopy prep

65
Q

What are the contraindications of Mg(OH)3?

A

CAUTION in pts with renal insufficiency

increases the risk of hypermagnesemia

66
Q

Loperamide

A

Anti-diarrheal
opioid OTC

poorly absorbed = low abuse potential

67
Q

What is the MOA of loperamide?

A

stimulation of mu opioid receptors in intestinal smooth muscle
slows intestinal transit time

68
Q

What are the adverse reactions of loperamide?

A

constipation

toxic megacolon

69
Q

When is loperamide contraindicated?

A

UC
acute bacillary ameobic dysentery (shigellosis)

d/t risk of megacolon

70
Q

What types of drugs can cause constipation?

A

anticholinergics

opioids (loperamide included)

71
Q

Alosetron

A

FDA approved for females with IBS - D
restricted drug d/t risk of ischemic colitis

MOA: 5HT3 receptor antagonist

72
Q

How do you treat IBS with predominant diarrhea?

A

Loperamide

Alosetron

73
Q

How do you treat IBS with predominant constipation?

A

Mg(OH)2 - osmotic laxative

tegaserod –emergency use only –must get FDA approval on case by case basis

74
Q

What drugs do you use for active IBD?

A

prednisone

rapidly reduces ulceration
decrease inflammatory response
ONLY short term therapy

75
Q

What drug is effective in maintaining remission of IBD?

A

Azathioprine

prodrug
antimetabolite that inhibits DNA synthesis

response take weeks to months

76
Q

What are the adverse effects of azathioprine and prednisone?

A 
bone marrow suppression 
pancreatitis 
elevated LFTs
rashes 
fever
nausea
77
Q

What is the first line treatment for UC?

A

5ASA - sulfasalazine

only works topically –colon

sulfasalazine (prodrug) 
|
|
|
5ASA (mesalamine) active drug
78
Q

PENTASA

A

Mesalamines most effective at delivering 5ASA to small intestine

79
Q

What is the first line treatment for CD?

A

Methotrexate (antimetabolite)
Infliximab (Remicade)
ABX - metronidazol, ciprofloxacin

80
Q

Infliximab

A

first line for CD
binds TNF alpha inhibiting inflammatory effects on TNF receptors
also approved for UC

81
Q

What are the adverse effects of Infliximab?

A

increase infections because it suppresses everything

Pharm 2 (6 decks)

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