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USMLE (S1) Gastrointestinal > Gastro - Pharmacology > Flashcards

Flashcards in Gastro - Pharmacology Deck (67)
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1
Q

Proton pump inhibitors work on pumps that exchange which two ions?

A

Hydrogen and potassium

2
Q

H2-blockers work on which stomach cell type?

A

Parietal cells

3
Q

Muscarinic antagonists work on which two cell types in the stomach?

A

Enterochromaffin-like cells (with M1 receptors) and parietal cells (with M3 receptors)

4
Q

Why are misoprostol, sucralfate, and bismuth beneficial in treatment of gastric ulcers?

A

These drugs have a protective effect on the mucosa underlying ulcers

5
Q

Give four examples of H2-blockers.

A

Cimetidine, ranitidine, famotidine, and nizatidine (remember: Take H2-blockers before you DINE)

6
Q

What substance is the endogenous agonist of the H2-receptor?

A

Histamine

7
Q

What is the effect of H2-blockers on parietal cells?

A

Reversible decrease of hydrogen ion secretion

8
Q

List three clinical uses of H2-blockers.

A

Peptic ulcer, gastritis, mild esophageal reflux

9
Q

Which H2-blocker has important toxicities that are not seen with other H2-blockers?

A

Cimetidine

10
Q

Cimetidine is a potent _____ of P450.

A

Inhibitor

11
Q

What effect does cimetidine have on the kidneys?

A

Decreased creatinine excretion

12
Q

Which two H2 blockers can decrease the renal excretion of creatinine?

A

Ranitidine and cimetidine

13
Q

Which adverse effects of cimetidine are seen specifically in males?

A

Prolactin release, gynecomastia, impotence, decreased libido

14
Q

By what mechanism does cimetidine cause confusion, dizziness and headaches?

A

It is able to cross the blood-brain barrier

15
Q

True or False? Cimetidine is safe during pregnancy.

A

False; cimetidine crosses the placenta

16
Q

Give at least two examples of proton pump inhibitors.

A

Omeprazole and lansoprazole

17
Q

Proton pump inhibitors work by inhibiting _____ _____ _____ in stomach parietal cells.

A

Hydrogen potassium adenosine triphosphatase

18
Q

What are the clinical indications for use of proton pump inhibitors?

A

Peptic ulcers, gastritis, esophageal reflux, and Zollinger-Ellison syndrome

19
Q

What is the mechanism of action of bismuth and sucralfate?

A

They provide a physical barrier in ulcers to protect from stomach acid

20
Q

What are two of the infectious indications for bismuth or sucralfate?

A

Traveler's diarrhea, Helicobacter pylori infection (as part of triple therapy)

21
Q

What are the three components of triple therapy?

A

Metronidazole, bismuth, and amoxicillin or tetracycline

22
Q

True or False? A proton pump inhibitor can also be used when treating an ulcer caused by Helicobacter pylori infection.

A

True (remember: Please MAke Tummy Better for drugs used to treat Helicobacter pylori infection: proton pump inhibitor, metronidazole, amoxicillin, tetracycline, bismuth)

23
Q

Misoprostol is a _____ ____ analogue.

A

Prostaglandin E1

24
Q

Misoprostol functions by increasing the production and secretion of the _____ _____ _____ and decreasing the production of _____.

A

Gastric mucous barrier; acid

25
Q

A woman with rheumatoid arthritis was recently started on misoprostol because of adverse effects of her arthritis medicine. What is the adverse effect and the medication that caused it?

A

Peptic ulcers induced by nonsteroidal antiinflammatory drugs

26
Q

A neonate becomes cyanotic on the third day of life despite 100% supplemental oxygen administration. The attending orders infusion of a medication and the neonate's oxygen saturation slowly returns to normal. What medication did the attending order an

A

Misoprostol; it maintains the patent ductus arteriosus thereby allowing mixing of pulmonary and systemic circulation in the case of congenital heart disease

27
Q

A woman presents to her OB/GYN at 42 weeks' gestation and is admitted to the hospital. You look at the orders and see that misoprostol is administered. What is the role of misoprostol in this patient?

A

To induce labor

28
Q

Within what population is misoprostol contraindicated?

A

Women of childbearing potential; it is an abortifacient

29
Q

In addition to being an abortifacient, what other toxicity does misoprostol have?

A

Diarrhea

30
Q

List two muscarinic antagonists that are used to treat peptic ulcers.

A

Pirenzepine and propantheline

31
Q

What are the two target cells of muscarinic antagonists when used to decrease acid secretion?

A

Enterochromaffin-like cells and parietal cells

32
Q

Muscarinic antagonists block what receptors on enterochromaffin-like cells?

A

M1 receptors

33
Q

By blocking the M1 receptors on enterochromaffin-like cells, muscarinic antagonists achieve what effect?

A

Decreased histamine secretion

34
Q

Muscarinic antagonists block what receptors on parietal cells?

A

M3 receptors

35
Q

By blocking the M3 receptors on parietal cells, muscarinic antagonists achieve what effect?

A

Decreased hydrogen secretion

36
Q

What are the muscarinic antagonists pirenzepine and propantheline used for clinically?

A

Peptic ulcers (rarely used)

37
Q

Name three major adverse effects caused by muscarinic antagonists.

A

Tachycardia, dry mouth, and difficulty focusing eyes (anticholinergic adverse effects)

38
Q

What effects can antacids have on the efficacy of other drugs?

A

Interference with absorption, bioavailability, and urinary excretion by altering gastric and urinary pH and delaying gastric emptying

39
Q

List three compounds that are commonly used as antacids.

A

Aluminum hydroxide, magnesium hydroxide, and calcium carbonate

40
Q

The overuse of the antacid aluminum hydroxide can cause what toxicities?

A

Constipation, hypophosphatemia, hypokalemia, proximal muscle weakness, osteodystrophy, seizures

41
Q

Diarrhea, hyporeflexia, hypotension, cardiac arrest and hypokalemia are side effects of which antacid?

A

Magnesium hydroxide; remember Mg = Must go to the bathroom

42
Q

Overuse of the antacid calcium carbonate can cause what three toxicities?

A

Hypercalcemia, rebound acid increase, and hypokalemia

43
Q

All antacids cause what electrolyte abnormality if overused?

A

Hypokalemia

44
Q

A patient who heavily self-medicates her gastroesophageal reflux disease complains of dizziness and diarrhea. Which antacid is she most likely overusing?

A

Magnesium hydroxide

45
Q

A patient has a witnessed first seizure. Afterward he complains of recent constipation and proximal muscle weakness. What medication is he most likely overusing to treat his gastroesophageal reflux disease?

A

Aluminum hydroxide; remember Aluminimum amount of feces

46
Q

A patient is found to have hypophosphatemia and osetodystrophy. What medication is he most likely chronically overusing to treat his gastroesophageal reflux disease?

A

Aluminum hydroxide

47
Q

A patient becomes hypotensive and hyporeflexive. She mentions that she has gastroesophageal reflux disease and takes large amounts of antacids. Which antacid is she most likely overusing?

A

Magnesium hydroxide

48
Q

What is the mechanism of action of infliximab?

A

It is a monoclonal antibody to tumor necrosis factor-a remember INFLIXimab INFLIX pain on TNF

49
Q

List two diseases that are treated with infliximab.

A

Crohn's disease and rheumatoid arthritis

50
Q

What test should be conducted before starting a patient on infliximab?

A

Purified protein derivative test; this medication can cause reactivation tuberculosis

51
Q

What are the adverse effects of infliximab?

A

Reactivation of latent tuberculosis, hypotension, fever

52
Q

Sulfasalazine is a combination of what two drugs?

A

Sulfapyridine and mesalamine

53
Q

What is the function of sulfapyridine?

A

It is an antibiotic

54
Q

What unique mechanism of delivery of mesalamine is created when it is combined with sulfapyridine?

A

It is activated by colonic bacteria

55
Q

Sulfasalazine is used to treat what two diseases?

A

Crohn's disease and ulcerative colitis

56
Q

What are the adverse effects of sulfasalazine?

A

Oligospermia, malaise, nausea, and sulfonamide toxicity

57
Q

A patient is found to have Crohn's ileitis. He asks if he can be started on sulfasalazine. What is the appropriate response?

A

Sulfasalazine would be ineffective because it is activated by colonic bacteria and thus has no effect proximal to the colon

58
Q

Ondansetron is an antagonist of what receptor type?

A

5-hydroxytryptamine3

59
Q

Ondansetron is used to control vomiting in which two situations?

A

After an operation and for patients getting cancer chemotherapy (remember: you will not vomit with ONDANSetron, so you can go ON DANCing)

60
Q

What are two toxicities of ondansetron?

A

Headache and constipation

61
Q

What is the mechanism of metoclopramide?

A

It is a dopamine receptor antagonist

62
Q

What specific dopamine receptor is blocked by metoclopramide?

A

D2 receptor

63
Q

With what drugs does metoclopramide interact?

A

Digoxin and diabetic agents

64
Q

Metoclopramide is contraindicated in patients with what serious gastrointestinal disorder?

A

Small bowel obstruction, because it is prokinetic and thus will worsen the discomfort of these patients

65
Q

On what parts of the gastrointestinal tract does metoclopramide act?

A

The lower esophageal sphincter (it increases tone and contractility), the stomach, and the small bowel (increases motility); it has no effect on the colon

66
Q

What are the clinical uses of metoclopramide?

A

Diabetic gastroparesis and postsurgical gastroparesis

67
Q

What are side effects of metoclopramide?

A

restlessness, drowsiness, fatigue, depression, nausea, diarrhea