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Pharmacology Exam 5 > GI Drugs > Flashcards

GI Drugs Flashcards

1
Q

What are the drug types used to treat peptic ulcer and GERD (5)?

A

Proton pump inhibitors, histamine H2 receptor antagonists, antacids, mucosal protective agents, antibiotics (for eradicating H. pylori)

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2
Q

Where is gastric acid secreted?

A

by parietal cells in the stomach

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3
Q

What receptors are on parietal cells?

A

histamine H2, cholinergic (muscarinic) and gastrin

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4
Q

What is the final step for gastric acid secretion?

A

activity of the proton pump (H-K ATPase)

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5
Q

where are proton pumps located?

A

within the canaliculus and in cytoplasmic tubulovesicles

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6
Q

does the distribution of proton pumps between the canaliculus and vesicles vary?

A

yes, according to cell activity

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7
Q

Under resting conditions, what is the percentage of pumps within the canaliculus?

A

5%

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8
Q

On stimulation of parietal cells (after a meal), what percentage of pumps are transferred to the canaliculus membrane?

A

60-70%

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9
Q

What happens to the pumps once cell activation stops?

A

pumps are recycled back to cytoplasmic vesicles

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10
Q

What is the pattern of basal acid production?

A

circadian pattern with highest levels occurring during the night

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11
Q

What inputs are the main contributors to basal acid secretion?

A

cholinergic and histaminergic inputs?

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12
Q

What is the main stimulant for increased acid secretion after meals?

A

Gastrin

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13
Q

What is the PPI to know?

A

Omeprazole

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14
Q

How are PPIs administered?

A

as inactive, acid-labile prodrugs. formulated with acid-resistant coating which dissolves in the intestine

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15
Q

what happens to the PPI prodrug in the intestine (3)?

A

1) the lipophilic base pro-drug is absorbed and enters into the canaliculus of the parietal cell
2) in this acid compartment of the canaliculus the pro-drug is protonated and concentrated >1000-fold
3) acid-activated drug blocks H-K-ATPase irreversibly by forming a covalent bond with SH-groups of H-K-ATPase

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16
Q

How much time is required for synthesis of new H-K-ATPase with Omeprazole and what is its half-life?

A

18 hours, half life is ~1hr but can affect acid secretion for 24 hours

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17
Q

How are PPIs (Omeprazole) prescribed?

A

given once daily, take 1 hr before meal so that coincides with max activity of proton pump secretion (bioavilability decreased to 50% with food)

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18
Q

How are PPIs used?

A

used in gastric ulcers, alone or in combo with antibiotics for H. pylori. high doses for a few days can inhibit gastric acid secretion up to 95%. also used in GERD, Zollinger-Ellison Syndrome.

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19
Q

What are the drug interactions of Omeprazole?

A

decreases the pharmacological activity of clopidogrel

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20
Q

What are the Histamine H2-receptor antagonists?

A

Cimetidine

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21
Q

How do histamine H2 receptor antagonists (Cimetidine) work (4)?

A

1) inhibit fasting secretion of gastric acid with a smaller effect on food-stimulated gastric acid secretion
2) competitive inhibitor at the parietal cell H2 receptor
3) blunt responses to Ach and gastrin
4) little or no effect on H1 receptors

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22
Q

When are Histamine H2-receptor antagonists (Cimetidine) used?

A

gastric ulcers, alone or in combo with antibiotics. also used in heartburn or GERD

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23
Q

What are the adverse effects of Cimetidine?

A

very safe, few adverse side effects

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24
Q

What are the drug interactions of Cimetidine?

A

interferes with metabolism of other drugs due to inhibition of cytochrome P-450.

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25
Q

Which are better: PPIs or H2-antagonists?

A

PPIs

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26
Q

What are the mucosal protective agents (3)?

A

Misoprostol, Sucralfate, Bismuth Subsalicylate

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27
Q

How does Misoprostol work (3)?

A

1) causes a modest inhibition of acid secretion by binding to PG reeptor
2) cytoprotective
3) promotes secretion of mucus and bicarbonate

28
Q

What is Misoprostol used for?

A

indicated for prevention of gastric damage during chronic use of NSAIDs

29
Q

What are some adverse effects of Misoprostol?

A

diarrhea, abdominal cramps

30
Q

What are contraindications of Misoprostol?

A

pregnancy! causes uterine contraction

31
Q

What is Sucralfate?

A

complex of Al(OH)3 and sulfated sucrose

32
Q

How does Sucralfate work (4)?

A

1) in an acid environment, sucralfate produces a viscous, sticky polymer.
2) cytoprotective
3) coats gastric mucosa
4) stimulates PGE production

33
Q

What are drug interactions of Sucralfate?

A

reduces absorption of digoxin and phenytoin

34
Q

What is Bismuth sunsalicylate and how does it work (3)?

A

Pepto-Bismol.

1) has a cytoprotectice action
2) binds to and coats ulcers.
3) may inhibit pepsin activity and increase mucus, prostaglandin, and bicarbonate secretion

35
Q

When is bismuth subsalicylate used?

A

mild diarrhea, eradication of H. pylori?, maybe some antibacterial effect against H. pylori

36
Q

Why might people not use bismuth subsalicylate?

A

bad taste

37
Q

What are some adverse effects of bismuth subsalicylate?

A

patients sensitive to aspirin may show sensitivity to salicylate

38
Q

Are there triple and quadruple therapies used to eradicate H. pylori?

A

duh.

39
Q

Which drugs stimulate GI motility?

A

Metoclopramide, Erythromycin

40
Q

How does Metoclopramide work (4)?

A

1) release Ach from cholinergiv neurons in myenteric plexus
2) enhances tone and otility in esophagus and stomach, facilitates gastric emptying. works on upper, but not lower, GI tract
3) stimulates gastric motility (prokinetic) without increasing acid secretion
4) is a dopamine D2 receptor antagonist and enters the CNS

41
Q

When is Metoclopramide used (5)?

A

GERD, reflux esophagitis (heartburn), disorders of gastric emptying (Diabetic gastroparesis) and intractable hiccup. used as anti-emetic (in cancer chemotherapy) due to its CNS action

42
Q

What are the adverse effects of Metoclopramide?

A

extrapyramidal effects (Parkinsonism)

43
Q

What are the contraindications of Metoclopramide?

A

contra’d in persons with seizure disorders and in mechanical obstruction of GI tract

44
Q

How does Erythromycin work (2)?

A

1) has also a prokinetic effect.

2) stimulates motilin receptors (a polypeptide hormone that mediates intestinal smooth muscle contraction)

45
Q

When is Erythromycin used?

A

diabetic gastroparesis, may be used in patients with upper GI hemorrhage to promote gastric emptying prior to endoscopy

46
Q

What’s up with vomiting (3)?

A

1) vomiting center (VC) is in medulla
2) emetic stimuli activate 5-HT3 receptors in stomach relay message to VC via solitary tract nucleus STN and chemoreceptor trigger zone CTZ
3) also reach VC from cerebral cortex and vestibular apparatus

47
Q

How do antiemetics work?

A

5-HT3 receptor antagonists

48
Q

What is the antiemetic to know?

A

Ondansetron

49
Q

How do the antiemetics work?

A

prevent peripheral and central stimulation of VC by blocking 5-HT3 receptors in the stomach, STN, and CTZ.

50
Q

What are the indications for antiemetics (2)?

A

1) used to prevent and treat cancer chemotherapy-induced emesis. Effective for immediate emesis due to chemotherapy
2) postoperative and post-radiation nausea and vomiting and in hyperemesis of pregnancy

51
Q

How often are antiemetics given?

A

one or twice daily (long half life)

52
Q

Who’s by far the coolest person in our whole class?

A

Jennnnnnnnnnnnnaaaaaaa (just playin’)

53
Q

Which drugs are used to treat inflammatory bowel disease (IBD, UC, CD) (6)?

A

5-ASA, Budesonide, Azathioprine, 6-Mercaptopurine, Methotrexate, Infliximab

54
Q

What is the aminosalicylate to know?

A

5-ASA = aminosalicylic acid

55
Q

How does 5-ASA work?

A

Who knows? probably not cyclooxygenase inhibition

56
Q

What is Budesonide and what should you know about it?

A

a synthetic analog of prednisolone, commonly used to treat moderate to severe flares but inappropriate for long-term use due to side effects

57
Q

What are the purine analogs?

A

Azathioprine and 6-Mercaptopurine

58
Q

How do the purine analogs work?

A

immunosuppressants

59
Q

What are the purine analogs used for?

A

important agents in the induction and maintenance of remission of ulcerative colitis and Crohn’s Disease

60
Q

What are the adverse effects of the purine analogs (Azathioprine and 6-Mercaptopurine) (4)?

A

nausea, vomiting, bone marrow suppression and hepatotoxicity.

61
Q

How does Methotrexate work?

A

may interfere with inflammatory action of IL-1, increase release of adenosine (anti-inflammatory actions), stimulate death of activated T-cells.

62
Q

What is Methotrexate used for?

A

used to induce and maintain remission in Crohn’s Disease

63
Q

What are the adverse effects of Methotrexate (3)? How can the risk of these side effects be reduced?

A

seen with higher doses: bone marrow suppression, megaloblastic anemia, alopecia. Reduce risk by supplementation with folate.

64
Q

What is Infliximab and how does it work?

A

monoclonal antibody to TNF-a. Binds to TNF-a so it is unable to bind to its receptor.

65
Q

What is Infliximab used for?

A

used in the acute and chronic treatment of moderate to severe Crohn’s disease and ulcerative colitis

66
Q

What are the adverse effects of Infliximab?

A

infection due to suppression of the TH1 inflammatory response.

67
Q

What are the drugs to know (14)?

A

Omeprazole, Cimetidine, Misoprostol, Sucralfate, Bismuth Subsalicylate, Metoclopramide, Erythromycin, Odansetron, 5-ASA, Budesonide, Azathioprine, 6-Mercaptopurine, Methotrexate, Infliximab

Pharmacology Exam 5 (9 decks)

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