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GI > PUD and GERD Med Chem (Dr. J) > Flashcards

PUD and GERD Med Chem (Dr. J) Flashcards

1
Q

What are stimulatory signals for HCl secretion?

A

Histamine
Ach
Gastrin

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2
Q

When histamine binds to the H2 receptor, what kind of GPCR is stimulating the proton pump?

A

Gs (adenylyl cyclase, cyclic AMP, PKA)

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3
Q

When Ach binds to the M3 receptor, what kind of GPCR is stimulating the proton pump?

A

Gq (PLC, IP3, Ca2+)

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4
Q

When gastrin binds to the CCK2 receptor, what kind of GPCR is stimulating the proton pump?

A

Gq (PLC, IP3, Ca2+)

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5
Q

What is the core structure of PPIs?

A

pyridine and benzimidazole moiety liked by methylsulfinyl group

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6
Q

Which PPIs are racemic mixtures?

A

Lansoprazole
Omeprazole
Pantoprazole
Rabeprazole

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7
Q

PPIs are prodrugs activated by _______ ___________

A

acidic environment

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8
Q

What happens when PPIs are in an acidic environment before reaching the site of action?

A

can bind to other proteins—> inactivated drug

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9
Q

What is the target reaction when PPI reaches the site of action?

A

sulphenamide interacts covalently with the sulphydryl groups of cysteine residues in extracellular domain of the proton pump

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10
Q

How long does it take for new proton pump molecules to be synthesized after taking PPI?

A

24-48 hours

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11
Q

PPIs need enteric coating to reach site of action, what dosage forms can PPIs come in?

A
  1. capsules
  2. powder for suspension
  3. tablets
  4. IV
  5. enteric coated granules
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12
Q

How do we prevent degradation of PPIs by acid outside of the desired site of action?

A

eteric coating

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13
Q

How are PPIs metabolized?

A

CYP2C19 and CYP 3A4 (1st pass metabolism)

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14
Q

How many days does it take to achieve a 70 % inhibition of proton pumps?

A

2-5 days

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15
Q

What type of environment do DR and enteric coated tablets dissolve in?

A

alkaline pH

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16
Q

What is a bioisotere?

A

mimic natural ligand but inhibit its natural action

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17
Q

What is the MOA of H2RAs?

A

inhibit acid production by reversibly competing with histamine for binding of H2 receptors on the basolateral membrane of parietal cells

18
Q

How much acid is suppressed by H2RAs in 24 hours?

A

70%

19
Q

Why is Ranitidine recalled?

A

NDMA (a carcinogen) increases over time under normal storage conditions

20
Q

What FG was added to ranitidine in order for NDMA not to form?

A

thiazole ring replaces furan

21
Q

What is absorption of H2RAs enhanced by?

A

food

22
Q

What is absorption of H2RAs decreased by?

A

antacids

23
Q

When do serum concentrations of H2RAs peak?

A

1-3 hours

24
Q

What neuro-endocrine cells are most prominent in acid-secreting regions of the stomach?

A

Enterochromaffin- like cells

25
Q

What are the cytoprotective effects of Prostaglandin E2?

A
  1. Stimulation of mucin
  2. Stimulation of bicarbonate secretion
  3. increased mucosal blood flow
26
Q

What does Misoprostol (EP3 agonist) on parietal cells result in?

A

decreased acid secretion (Gi mediated)

27
Q

How can pepsin-mediated hydrolysis of mucosal proteins leading to mucosal erosion and ulcerations be inhibited?

A

sulfated polysaccharides (sucralfate)

28
Q

How does sucralfate produce a physical and chemical barrier?

A

cross-linking produces a sticky polymer that adheres to epithelial cells and ulcer craters

29
Q

Why does CaCO3 (antacid) produce more gas and pain as a side effect?

A

produces CO2 as a byproduct; can cause belching, distention, flatulence

30
Q

How does food effect antacids?

A

Food elevates gastric pH to ~5 for ~1hour and prolongs the effects of antacids for ~2-3 hours

31
Q

What properties of antacids can cause drug interactions?

A

Alter gastric and urinary pH

32
Q

Antacids can _________ other drugs due to Mg2+ and Al3+

A

Chelate

33
Q

Which type of ulcer is more dependent on intragastric pH?

A

H. Pylori

34
Q

H.pylori is significantly less common in places with _______ socioeconomic status

A

High

35
Q

When is H. Pylori usually contracted and how long does it last?

A

Early child hood; can be dormant for life

36
Q

How is H.pylori able to adhere to epithelial cells?

A

Uses flagella to swim through the mucus layer of the stomach/ intestines where pH is near neutral

37
Q

What mechanism does H.pylori use to protect itself from acidic environment?

A

Produces acid inhibitory protein that blocks acid secretion by parietal cells

38
Q

How does H. Pylori lead to excessive production of cytokines and inflammation?

A

Release toxins

39
Q

How does our immune system destroy the mucosa when trying to eradicate H. Pylori?

A
  1. Neutrophils leave capillaries and accumulate in areas of infection
  2. Release lysosomes for extracellular killing
  3. Destroys bacteria and mucous membranes of stomach
  4. Gastric acid causes ulcerations
40
Q

How does chronic gastritis due to H. Pylori affect other systems in the body?

A

Production of gastrointestinal hormones (somatostatin, gastrin, ghrelin) and neurotransmitters

41
Q

What other problems can chronic H. Pylori infection lead to?

A

MALT lymphoma
Intestinal metaplasia
Dysplasia
Gastric cancer

GI (23 decks)

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