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Pharm 2 > Lecture 3 - GI Drugs > Flashcards

Lecture 3 - GI Drugs Flashcards

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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
Are PPIs available OTC?
yes | Prilosec
26
When is gastrin secreted and what does it do?
Gastrin is released in response to stretch of the stomach and stimulates acid production not produced at night
27
Sucralfate
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
28
What are the risk factors of PUD?
``` presence of H. pylori NSAIDS salicylates (aspirin) Tobacco Heredity and age ```
29
When do you instruct your patients to take sucralfate?
BEFORE they eat
30
What must you tell your patient who are taking sucralfate in addition to other drugs as far as WHEN to take these drugs?
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
31
Which drugs can be absorbed by sucralfate?
tetracylcine phenytoin digoxin
32
Why don't you want to coadmin antacids with sucralfate?
because sulcrafate needs an acidic environment to form paste and be protective
33
Is sucralfate absorbed?
no
34
Bismuth subsalicylate
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
Can you give bismuth subsalicylate to children?
no | salicylic avid --Reye's syndrome
36
What do you have to advise your pts who are going to start taking bismuth subsalicylate?
don't worry if your stool or tongue turn black, that is a typical SE of the drug since it gets absorbed
37
Misoprostol
mucosal protective agent PG1 analog blocks acid secretion on ECL and parietal cell via G protein
38
What are the contraindications of Misoprostol?
Pregnancy | since its a prostaglandin analog and PGs can induce contractions
39
What are different ways to decrease acid in the stomach?
block H2 receptors on parietal cells | enhance somatostatin release or give somatostatin analog (somatostatin blocks everything)
40
What are different ways to treat ZES?
PPI | somataostatin analog
41
What controls the vomiting center?
ACh
42
What stimuli can cause vomiting?
- motion sickness - pain, repulsive sights, smells, emotional factors - endogenous toxins, durgs - stimuli from pharynx and stomach
43
CTZ
chemotrigger zone | feeds directly into vomiting center
44
Where is the majority of seretonin secreted?
the gut
45
Metoclopramide
anti-emetic prokinetic D2 receptor antagonist 5HT3 receptor antagonist 5HT4 receptor agonist cholinergic stimulant
46
How does metoclopramide work as an antiemetic?
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
What drug is used in chemo drug induced N/V?
metoclopramide
48
What are the adverse effects of metoclopramide?
dopamine D2 receptor antagonist can cause extrapyramidal (Parkinsons like) sxs and tradive dykinesia BBW - long term use - irreversible muscle spasm (dyskinesia)
49
What can occur with long term use of metoclopramide?
irreversible muscle spasm (dyskinesia)
50
Odansatron
PO, IV selective 5HT3 receptor antagonist give PRIOR to chemotherapy or surgery little to no effect on muscarinic or dopaminergic receptors Adverse: constipation
51
What are the side effects of odansatron?
constipation
52
When do you give odansatron?
PRIOR to surgery or chemotherapy
53
Besides D2 receptor antagonists and 5HT3 receptor antagonists, what are other targets for antiemetics?
H1 receptor antagonists Muscarinic antagonists Neurokinin 1 antagonists
54
Types of laxative
fiber lubiprostone linaclotide Mg(OH)2
55
What are contraindications of laxatives?
cramps colic N/V abdominal pain undx
56
Lubiprostone indications
IBS w/ constipation | idiopathic chronic constipation
57
What is the MOA for lubiprostone?
``` ClC2 CL channel activator increases intestinal fluid secretion increases number of bowel movements acts luminally (minimally absorbed) ```
58
What are the adverse effects of lubiprostone?
diarrhea, N, abdominal pian, distention
59
What are the indications for Linaclotide?
IBS w. constipation | idiopathic chronic constipation
60
What is the MOA of linaclotide?
activation of cystic fibrosis transmembrane conductance regulator (CFTR) increase intestinal fluid secretions increase number of bowel movements acts luminally (minimal absorption)
61
What are the adverse effects of linaclotide?
diarrhea
62
What are the contraindications of linaclotide?
in peds pts d/t dehydration related deaths
63
Saline laxative
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
Cathartic dose
Mg(OH)3 complete evacuation of bowel in 3 hours used for colonoscopy prep
65
What are the contraindications of Mg(OH)3?
CAUTION in pts with renal insufficiency | increases the risk of hypermagnesemia
66
Loperamide
Anti-diarrheal opioid OTC poorly absorbed = low abuse potential
67
What is the MOA of loperamide?
stimulation of mu opioid receptors in intestinal smooth muscle slows intestinal transit time
68
What are the adverse reactions of loperamide?
constipation toxic megacolon
69
When is loperamide contraindicated?
UC acute bacillary ameobic dysentery (shigellosis) d/t risk of megacolon
70
What types of drugs can cause constipation?
anticholinergics | opioids (loperamide included)
71
Alosetron
FDA approved for females with IBS - D restricted drug d/t risk of ischemic colitis MOA: 5HT3 receptor antagonist
72
How do you treat IBS with predominant diarrhea?
Loperamide | Alosetron
73
How do you treat IBS with predominant constipation?
Mg(OH)2 - osmotic laxative tegaserod --emergency use only --must get FDA approval on case by case basis
74
What drugs do you use for active IBD?
prednisone rapidly reduces ulceration decrease inflammatory response ONLY short term therapy
75
What drug is effective in maintaining remission of IBD?
Azathioprine prodrug antimetabolite that inhibits DNA synthesis response take weeks to months
76
What are the adverse effects of azathioprine and prednisone?
``` bone marrow suppression pancreatitis elevated LFTs rashes fever nausea ```
77
What is the first line treatment for UC?
5ASA - sulfasalazine only works topically --colon ``` sulfasalazine (prodrug) | | | 5ASA (mesalamine) active drug ```
78
PENTASA
Mesalamines most effective at delivering 5ASA to small intestine
79
What is the first line treatment for CD?
Methotrexate (antimetabolite) Infliximab (Remicade) ABX - metronidazol, ciprofloxacin
80
Infliximab
first line for CD binds TNF alpha inhibiting inflammatory effects on TNF receptors also approved for UC
81
What are the adverse effects of Infliximab?
increase infections because it suppresses everything

Pharm 2 (6 decks)

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