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GI Fitzy > Tx for acid-peptic diseases > Flashcards

Tx for acid-peptic diseases Flashcards

1
Q

A person has H. pylori positive ulcers, what antimicrobials are the most effective?

A 
Amoxicillin 
Clarithromycin 
Metronidazole/Tinidazole
Rifabutin 
Tetracycline
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2
Q

What is the MoA of amoxicillin? Why is amoxicillin better than ampicillin/anti-pseudomonals to treat H. pylori?

A

Amoxicillin is a transpeptidase inhibitor…beta-lactam

Amoxicillin is more acid stable and has a higher oral availability than ampicillin
Anti-pseudomonals are not orally available

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3
Q

What is the MoA of clarithromycin? Why is clarithromycin better than the other macrolides for H. pylori treatment?

A

Clarithromycin binds to to 50S subunit…inhibits peptidyltransferase

Clarithromycin has the lowest MIC50 (Minimal Inhibitory Concentration needed to inhibit 50%) and is more acid stable

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4
Q

What is the MoA of metronidazole/tinidazole? What are the down sides to metronidazole? What are some drug interactions to pay attention to?

A

Metronidazole/tinidazole are reduced in bacteria to active form…forms random linkages in bacterial enzymes/proteins

H. pylori are often resistant to metronidazole
There are many side effects

Metronidazole increases anticoagulant effect of warfarin
Cimetidine decreases plasma clearance of metronidazole

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5
Q

What is the MoA of rifabutin? What are some side effects of rifabutin?

A

Rifabutin is a rifampin analog…prevents elongation of RNA

Hypersensitivity/fever, hepatotoxicity, induction of CYP450, orange/red body fluids

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6
Q

What is the MoA of tetracycline? What should NOT be given with tetracycline? What SHOULD be done 1-2 hours after taking tetracycline?

A

Tetracycline binds to 30S subunit…prevents tRNA from binding to A site

Antacids should NOT be given with tetracycline…decreases efficacy due to chelation

Patient should eat…decreases absorption –> higher concentration in the stomach

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7
Q

What are examples of H2 receptor blockers?

A

Cimetidine
Famotidine
Nizatidine
Ranitidine

-tidine

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8
Q

Which H2 drug has the most side effects?

A

Cimetidine may cause dizziness or headaches…it is also a CYP450 inhibitor

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9
Q

Which drugs are the most effective at reducing intragastric acidity? How do they do this?

A

Proton pump inhibitors are the most effective

Proton pump inhibitors IRREVERSIBLY block H/K ATPase

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10
Q

What are examples of proton pump inhibitors?

A

Omeprazole/esomeprazole
Rabeprazole
Lansoprazole
Pantoprazole

-prazole

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11
Q

What are examples of weak bases used to buffer stomach acid?

A

Aluminum Hydroxide
Calcium Carbonate
Magnesium Hydroxide
Sodium Bicarbonate

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12
Q

What causes the difference in efficacy of the antacids?

A

Degree of systemic absorption (systemic is bad)
Rate of dissolution and reactivity
Effects of cations and/or reaction products (Al–> constipation; Mg–> diarrhea; carbonate–> increased CO2–> gastric distention and belching…give simethicone)

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13
Q

When should antacids be used? Why?

A

Antacids should be used for intermittent dyspepsia

Rapid onset with short duration
Antacids do NOT prevent ulcer recurrence

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14
Q

Histamine blockers are used more often than antacids: what are the major differences?

A

Histamine blockers also have a relatively rapid onset, but have a longer duration and can somewhat prevent ulcer recurrence

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15
Q

When should PPIs be used? Why?

A

Zollinger-Ellison Syndrome
GERD
Ulcer treatment

PPIs have slow onset, very long duration, and are excellent at preventing ulcer recurrence

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16
Q

What two drugs are essentially band-aids that give the stomach epithelium time to heal?

A

Sucralfate and Bismuth

17
Q

What is the MoA of sucralfate? When is it used?

A

Sucralfate stimulates secretion of PGs and bicarb…also recruit growth factors

Sucralfate is used in ICU…PPIs increase risk of pneumonia

18
Q

What is a possible side effect of sucralfate?

A

Sucralfate causes constipation in 2-4% of patients…d/t aluminum salt

19
Q

What is the MoA of bismuth?

A

Little antimicrobial activity…disrupts cell wall, prevents adhesion, and inhibits urease

Protects ulcer surface by coating it and stimulating secretion of PGs, mucous, and bicarb

20
Q

What should be used to treat NSAID-induced ulcers?

A

Misoprostol is a synthetic PG

21
Q

What is a neat thing for arthritis patients who have ulcers?

A

Misoprostol and NSAIDs can be given at the same time…pharmacokinetics are different enough

22
Q

What are the down sides to misoprostol?

A

Increased intestinal electrolyte and fluid secretion –> dose dependent diarrhea, severe nausea, and cramping (10-20% of patients)

CANNOT give to pregnant women

23
Q

What are the side effects of PPIs?

A

Alter absorption of other drugs/vitamins/minerals from the GI tract

Increase gastrin levels

If H. pylori not treated –> increased gastric inflammation

Rarely headache, diarrhea, ab pain, nausea or rash

Increased risk of respiratory and enteric infections

24
Q

What is the difference between omeprazole and esomeprazole?

A

Omeprazole is racemic mixture (OTC)

Esomeprazole is only active S-isomer (prescription)

25
Q

How do PPIs get to the parietal cell canaliculi?

A

Administered with enteric coating or with NaCO3…allows drug to make it to intestinal lumen (must be given in fasting state)

Prodrugs get absorbed and circulate…prefer acidic places where they can be protonated/activated (pumps must be active…give drug 1hr before eating)

26
Q

How often do PPIs have to be taken?

A

Once daily…takes 3-4 days to reach full effect

27
Q

What are some muscarinic drugs that could be used to treat ulcers? Why aren’t these drugs used to treat ulcers?

A

Atropine and Pirenzipine

Antimuscarinics will slow gastric emptying…they also have more/worse side effects than H2 inhibitors

28
Q

Is there a significant difference b/w prescription and OTC antihistamines?

A

OTC will have to be taken 4 times a day

Prescription will have to be taken twice daily

29
Q

What is special about nizatidine?

A

Nizatidine has 100% bioavailability…very little first pass metabolism

30
Q

What are the key components to H. pylori ulcer treatments?

A

Multiple antibiotics

Pain treatment

31
Q

What is the current standard?

A

Triple therapy

PPI + (clarithromycin (5 days) and then amoxicillin or tinidazole for 5 days)

32
Q

What are possible treatment methods if the triple therapy fails to treat H. pylori ulcers?

A

PPI + bismuth + tetracycline + metronidazole for 14 days

PPI + amoxicillin + rifabutin + ciprofloxacin for 10 days

33
Q

What are some side effects of tetracycline?

A

GI irritation
Photosensitivity
DON’T give to PREGOS

GI Fitzy (6 decks)

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