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Pharmacology -- Test #5 > Gastrointestinal Drugs > Flashcards

Gastrointestinal Drugs Flashcards

1
Q

Three main types of GI drugs altering secretion

A

Antacids, H2 antagonists, proton pump inhibitors

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2
Q

What is Barrett’s Esophagus

A

Transition from stratified squamous epi to simple columnar

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3
Q

How do dietary peptides trigger acid release?

A
  1. Activation of G cell to release gastrin into antrum BV
  2. Gastrin hits ECL cell in fundus, triggers Histamine release
  3. Histamine triggers H+ release from parietal cells
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4
Q

Why doesn’t acid always cause ulcers?

A

Barrier or mucosa + bicarb

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5
Q

Which prostaglandins work with NO to maintain mucosal defenses of the stomach

A

PGE2, PGI2

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6
Q

Why do NSAIDS cause ulcers?

A

Inhibition on the PGE/I 2 that acts on EP3 to promote mucus and HCO3- release

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7
Q

Name the four more common antacids and their most important adverse effects

A

NaHCO3 – Alkalosis, Fluid Retention
CaCO3 – Milk Alkali syndrome
Al(OH)3 – Constipation
Mg(OH)2 – Diarrhea

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8
Q

What is Tums?

A

CaCO3

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9
Q

What is Maalox, Mylanta?

A

Al(OH)3 + Mg(OH)2

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10
Q

What is Gaviscon?

A

Sodium Alginate + Antacids

Prevents Reflux/GERD

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11
Q

What is Simethicone (Mylicon, Phazyme)

A

Mild Surfactant to help with gas release

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12
Q

What chemical component of drugs is common amongst H2 receptor antagonists

A

Amidazole Mimics

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13
Q

Important 1st generation H2 blocker

A

Cimetidine (Tagamet)

A competitive antagonist of the H2 receptor

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14
Q

Cimetidine may inhibit the activity of Cyp ___

A

2C6 + 2D9

Watch out for warfarin, phenytoin, benzos, sulfas

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15
Q

Side effects of Cimetidine

A

CNS effects
Anti-androgen
Inhibition of estradiol metab (galactorrhea)
Thrombocytopenia

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16
Q

Name the second generation H2 blockers

A

Ranitidine (Zantac)
Nizatidine (Axid)
Famotidine (Pepcid)

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17
Q

Effect of 2nd gen H2 blockers on OH

A

Increase bioavailability by reducing first pass balance

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18
Q

What makes a 2nd gen H2 blocker bettwe than Cimetidine?

A

Less CYP influence, Greater Potency

Once daily

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19
Q

What are proton pump inhibitors (concept)

A

Prodrugs that become irreversible inhibitors of H/K ATPase

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20
Q

Describe the mechanism of omeprazole fxn

A
  1. Add an H+ to form Sulfenic Acid
  2. Dehydration to Cyclinc Sulfenamide
  3. Irreversible binding to HK ATPase
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21
Q

Adverse effects of proton pump inhibitors

A

Nausea
B12 Deficiency
Osteoporotic Fracture if frequently used

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22
Q

Relationship of proton pump inhibitors and the CYPs

A

Inhibitors of CYP2C19
Builds up Diazepam, Warfarin , Phenytoin
Decreased Plavix activity

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23
Q

Risk of discontinuing treatment with H2 blocker or PP inhib.?

A

Acid rebound

No residual somatostatin inhib of gastrin secretion

24
Q

Two mucosal protective agents he mentioned

A

Sucralfate (Carafate)

Misoprostol (Cytotec)

25
Q

Why would you use a mucosal protective agent instead of an H2Block or PPI?

A

Severely ill patients at a high risk of nosocomial infection

26
Q

How does sucralfate (carafate) work?

A

After acid activation, Polymerizes and forms protective barrier at ulcer site

27
Q

Sucralfate (carafate) decreases absorption of…

A

tetracycline
digoxin
phenytoin

28
Q

How does misoprostol work?

A

It is a Prost. E1 derivative that reduces acid secretion and enhances mucus and bicarb secretion

29
Q

How is misoprostol used?

A

w/ chronic NSAIDS

30
Q

Adverse effects of Misoprostol?

A

Diarrhea

Abortions

31
Q

Combination therapy for H Pylori includes…

A

Bismuth salt
Antibiotic
H2 block or PPI (to heal the ulcer)

32
Q

Antibiotics typically used for H pylori

A

Metronidazole
Tetracycline
Amoxicilin
Clarithromycin

33
Q

What does bismuth subsalicylicylate do?

A

Antibacterial, Antiviral, and anti-secretory

Treatment for mild diarrhea, h pylori eradication

34
Q

On a cholinergic motor neuron in the gut, what receptors are activated when getting the go signal from ENS? What drugs target this?

A

5-HT4 – 5-HT

Motilin – Erythromycin

35
Q

Role of dopamine 2 receptor on the enteric cholinergic motor neuron

A

Dopamine inhibits signalling

Metoclopramide inhibits dopamine activity (increasing signalling and also anti-emetic effects)

36
Q

How does atropine influence GI motor activity? Neotigmine?

A

Atropine inhibits M3 receptor

Neostigmine is an acetylcholinesterase

37
Q

Clinically, why gice metoclopramide (reglan)?

A

Small bowel intubation
Post-Op+Diabetic Gastroparesis
GERD
Anti-emetic

38
Q

Side effects of Metoclopramide?

A

Sedation
Parkinson’s-like syndrome
Hyperprolactinemia

39
Q

5-HT4 agonists used as prokinetics?

A

Cisapride (propulsid)

  • Tegaserod - withdrawn from CV tox
  • Prucalopride - unavailable in US
40
Q

Motilin agonist used as pro kinetic?

A

Erythromycin

rapid tolerance = limited usefulness

41
Q

What is Linaclotide?

A

Peptide activators of guanylate cyclase 2

42
Q

What is linaclotide used to treat?

A

IBS+Constipation

Idiopathic Constipation

43
Q

Main adverse effect of linaclotide?

A

Diarrhea

44
Q

Why does linaclotide turning on guanylate cyclase 2 matter?

A
  1. Conversion of GTP to cGMP triggers CFTR receptor activity. This will increase H2O and electrolyte loss –> laxative effect.
  2. cGMP will also move extracellularly to decrease activity of pain sensing fibers
45
Q

Important Secretory/Stimulant Laxatives

A 
Bisacodyl (Dulcolax)
Cascara
Senna
Aloes
Lubiprostone
46
Q

What is Lubiprostone all about?

A

ClC2 activator for chronic idiopathic constipation

Used in IBS w/ chronic constipation

47
Q

Important Bulk laxatives

A

Psyllium, Methylcellulose, Bran, Milk of Magnesia

Lactulose

48
Q

lactulose is also used in patients with…

A

hepatic encephalopathy

49
Q

Isoosmotic electrolyte solutions with _______ produce similar effects to bulk laxatives

A

Polyethelene Glycol

50
Q

Important listed stool softeners

A

Docusate sodium (Colace)
Mineral Oil
Glycerin

51
Q

What are stool softeners?

A

Surfactants and lubricants that incorporate into stool to make passage easier

52
Q

How do anti-diarrheals work (broadly)

A
  1. Slow peristalsis to increase water + electro. absorp.

2. Absorp potential intestinal toxins + Water

53
Q

Anticholinergic used as an antidiarrheal?

A

Dicyclomine (Bentyl)

54
Q

Opiate use as an antidiarrheal?

A

Diphenoxylate (w/Atropine = Lomotil)

Loperamide (Imodium)

55
Q

Who should not get an optiate anti-diarrheal?

A

Patients with severe ulcerative colitis and bacterially induced diarrhea

56
Q

Name two kinds of antidiarrheals that stick around and grab stuff up to help out the diarrh.

A

Kaolin (attapulgite) and pectin

Low dose fiber

57
Q

What should you use to treat abdominal pain and distension + altered bowel habits in a woman w/ IBS

A

Alosetron (lotronex), a 5HT3 antagonist

This will lower the ACh release from the motor neurons, blocking visceral afferent pain and decreasing motility)

Pharmacology -- Test #5 (12 decks)

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