Gastro - Pharmacology

Question 1

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

Answer 1

Hydrogen and potassium

Question 2

H₂-blockers work on which stomach cell type?

Answer 2

Parietal cells

Question 3

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

Answer 3

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

Question 4

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

Answer 4

These drugs have a protective effect on the mucosa underlying ulcers

Question 5

Give four examples of H₂-blockers.

Answer 5

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

Question 6

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

Answer 6

Histamine

Question 7

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

Answer 7

Reversible decrease of hydrogen ion secretion

Question 8

List three clinical uses of H₂-blockers.

Answer 8

Peptic ulcer, gastritis, mild esophageal reflux

Question 9

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

Answer 9

Cimetidine

Question 10

Cimetidine is a potent _____ of P450.

Answer 10

Inhibitor

Question 11

What effect does cimetidine have on the kidneys?

Answer 11

Decreased creatinine excretion

Question 12

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

Answer 12

Ranitidine and cimetidine

Question 13

Which adverse effects of cimetidine are seen specifically in males?

Answer 13

Prolactin release, gynecomastia, impotence, decreased libido

Question 14

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

Answer 14

It is able to cross the blood-brain barrier

Question 15

True or False? Cimetidine is safe during pregnancy.

Answer 15

False; cimetidine crosses the placenta

Question 16

Give at least two examples of proton pump inhibitors.

Answer 16

Omeprazole and lansoprazole

Question 17

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

Answer 17

Hydrogen potassium adenosine triphosphatase

Question 18

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

Answer 18

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

Question 19

What is the mechanism of action of bismuth and sucralfate?

Answer 19

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

Question 20

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

Answer 20

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

Question 21

What are the three components of triple therapy?

Answer 21

Metronidazole, bismuth, and amoxicillin or tetracycline

Question 22

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

Answer 22

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

Question 23

Misoprostol is a _____ ____ analogue.

Answer 23

Prostaglandin E₁

Question 24

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

Answer 24

Gastric mucous barrier; acid

Question 25

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?

Answer 25

Peptic ulcers induced by nonsteroidal antiinflammatory drugs

Question 26

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

Answer 26

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

Question 27

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?

Answer 27

To induce labor

Question 28

Within what population is misoprostol contraindicated?

Answer 28

Women of childbearing potential; it is an abortifacient

Question 29

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

Answer 29

Diarrhea

Question 30

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

Answer 30

Pirenzepine and propantheline

Question 31

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

Answer 31

Enterochromaffin-like cells and parietal cells

Question 32

Muscarinic antagonists block what receptors on enterochromaffin-like cells?

Answer 32

M₁ receptors

Question 33

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

Answer 33

Decreased histamine secretion

Question 34

Muscarinic antagonists block what receptors on parietal cells?

Answer 34

M3 receptors

Question 35

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

Answer 35

Decreased hydrogen secretion

Question 36

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

Answer 36

Peptic ulcers (rarely used)

Question 37

Name three major adverse effects caused by muscarinic antagonists.

Answer 37

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

Question 38

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

Answer 38

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

Question 39

List three compounds that are commonly used as antacids.

Answer 39

Aluminum hydroxide, magnesium hydroxide, and calcium carbonate

Question 40

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

Answer 40

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

Question 41

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

Answer 41

Magnesium hydroxide; remember Mg = Must go to the bathroom

Question 42

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

Answer 42

Hypercalcemia, rebound acid increase, and hypokalemia

Question 43

All antacids cause what electrolyte abnormality if overused?

Answer 43

Hypokalemia

Question 44

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

Answer 44

Magnesium hydroxide

Question 45

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?

Answer 45

Aluminum hydroxide; remember Alu**minimum** amount of feces

Question 46

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

Answer 46

Aluminum hydroxide

Question 47

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?

Answer 47

Magnesium hydroxide

Question 48

What is the mechanism of action of infliximab?

Answer 48

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

Question 49

List two diseases that are treated with infliximab.

Answer 49

Crohn's disease and rheumatoid arthritis

Question 50

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

Answer 50

Purified protein derivative test; this medication can cause reactivation tuberculosis

Question 51

What are the adverse effects of infliximab?

Answer 51

Reactivation of latent tuberculosis, hypotension, fever

Question 52

Sulfasalazine is a combination of what two drugs?

Answer 52

Sulfapyridine and mesalamine

Question 53

What is the function of sulfapyridine?

Answer 53

It is an antibiotic

Question 54

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

Answer 54

It is activated by colonic bacteria

Question 55

Sulfasalazine is used to treat what two diseases?

Answer 55

Crohn's disease and ulcerative colitis

Question 56

What are the adverse effects of sulfasalazine?

Answer 56

Oligospermia, malaise, nausea, and sulfonamide toxicity

Question 57

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

Answer 57

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

Question 58

Ondansetron is an antagonist of what receptor type?

Answer 58

5-hydroxytryptamine₃

Question 59

Ondansetron is used to control vomiting in which two situations?

Answer 59

After an operation and for patients getting cancer chemotherapy (remember: you will not vomit with **ONDANS**etron, so you can go **ON DANC**ing)

Question 60

What are two toxicities of ondansetron?

Answer 60

Headache and constipation

Question 61

What is the mechanism of metoclopramide?

Answer 61

It is a dopamine receptor antagonist

Question 62

What specific dopamine receptor is blocked by metoclopramide?

Answer 62

D₂ receptor

Question 63

With what drugs does metoclopramide interact?

Answer 63

Digoxin and diabetic agents

Question 64

Metoclopramide is contraindicated in patients with what serious gastrointestinal disorder?

Answer 64

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

Question 65

On what parts of the gastrointestinal tract does metoclopramide act?

Answer 65

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

Question 66

What are the clinical uses of metoclopramide?

Answer 66

Diabetic gastroparesis and postsurgical gastroparesis

Question 67

What are side effects of metoclopramide?

Answer 67

restlessness, drowsiness, fatigue, depression, nausea, diarrhea