Gastro - Pharmacology Flashcards
Proton pump inhibitors work on pumps that exchange which two ions?
Hydrogen and potassium
H2-blockers work on which stomach cell type?
Parietal cells
Muscarinic antagonists work on which two cell types in the stomach?
Enterochromaffin-like cells (with M1receptors) and parietal cells (with M3 receptors)
Why are misoprostol, sucralfate, and bismuth beneficial in treatment of gastric ulcers?
These drugs have a protective effect on the mucosa underlying ulcers
Give four examples of H2-blockers.
Cimetidine, ranitidine, famotidine, and nizatidine (remember: Take H2-blockers before you DINE)
What substance is the endogenous agonist of the H2-receptor?
Histamine
What is the effect of H2-blockers on parietal cells?
Reversible decrease of hydrogen ion secretion
List three clinical uses of H2-blockers.
Peptic ulcer, gastritis, mild esophageal reflux
Which H2-blocker has important toxicities that are not seen with other H2-blockers?
Cimetidine
Cimetidine is a potent _____ of P450.
Inhibitor
What effect does cimetidine have on the kidneys?
Decreased creatinine excretion
Which two H2blockers can decrease the renal excretion of creatinine?
Ranitidine and cimetidine
Which adverse effects of cimetidine are seen specifically in males?
Prolactin release, gynecomastia, impotence, decreased libido
By what mechanism does cimetidine cause confusion, dizziness and headaches?
It is able to cross the blood-brain barrier
True or False? Cimetidine is safe during pregnancy.
False; cimetidine crosses the placenta
Give at least two examples of proton pump inhibitors.
Omeprazole and lansoprazole
Proton pump inhibitors work by inhibiting _____ _____ _____ in stomach parietal cells.
Hydrogen potassium adenosine triphosphatase
What are the clinical indications for use of proton pump inhibitors?
Peptic ulcers, gastritis, esophageal reflux, and Zollinger-Ellison syndrome
What is the mechanism of action of bismuth and sucralfate?
They provide a physical barrier in ulcers to protect from stomach acid
What are two of the infectious indications for bismuth or sucralfate?
Traveler’s diarrhea, Helicobacter pylori infection (as part of triple therapy)
What are the three components of triple therapy?
Metronidazole, bismuth, and amoxicillin or tetracycline
True or False? A proton pump inhibitor can also be used when treating an ulcer caused by Helicobacter pylori infection.
True (remember: Please MAke Tummy Better for drugs used to treat Helicobacter pylori infection: proton pump inhibitor, metronidazole, amoxicillin, tetracycline, bismuth)
Misoprostol is a _____ ____ analogue.
Prostaglandin E1
Misoprostol functions by increasing the production and secretion of the _____ _____ _____ and decreasing the production of _____.
Gastric mucous barrier; acid
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?
Peptic ulcers induced by nonsteroidal antiinflammatory drugs
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 and how does it improve the cyanosis?
Misoprostol; it maintains the patent ductus arteriosus thereby allowing mixing of pulmonary and systemic circulation in the case of congenital heart disease
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?
To induce labor
Within what population is misoprostol contraindicated?
Women of childbearing potential; it is an abortifacient
In addition to being an abortifacient, what other toxicity does misoprostol have?
Diarrhoea
List two muscarinic antagonists that are used to treat peptic ulcers.
Pirenzepine and propantheline
What are the two target cells of muscarinic antagonists when used to decrease acid secretion?
Enterochromaffin-like cells and parietal cells
Muscarinic antagonists block what receptors on enterochromaffin-like cells?
M1 receptors
By blocking the M1 receptors on enterochromaffin-like cells, muscarinic antagonists achieve what effect?
Decreased histamine secretion
Muscarinic antagonists block what receptors on parietal cells?
M3 receptors
By blocking the M3 receptors on parietal cells, muscarinic antagonists achieve what effect?
Decreased hydrogen secretion
What are the muscarinic antagonists pirenzepine and propantheline used for clinically?
Peptic ulcers (rarely used)
Name three major adverse effects caused by muscarinic antagonists.
Tachycardia, dry mouth, and difficulty focusing eyes (anticholinergic adverse effects)
What effects can antacids have on the efficacy of other drugs?
Interference with absorption, bioavailability, and urinary excretion by altering gastric and urinary pH and delaying gastric emptying
List three compounds that are commonly used as antacids.
Aluminum hydroxide, magnesium hydroxide, and calcium carbonate
The overuse of the antacid aluminum hydroxide can cause what toxicities?
Constipation, hypophosphatemia, hypokalemia, proximal muscle weakness, osteodystrophy, seizures
Diarrhea, hyporeflexia, hypotension, cardiac arrest and hypokalemia are side effects of which antacid?
Magnesium hydroxide; remember Mg = Must go to the bathroom
Overuse of the antacid calcium carbonate can cause what three toxicities?
Hypercalcemia, rebound acid increase, and hypokalemia
All antacids cause what electrolyte abnormality if overused?
Hypokalemia
A patient who heavily self-medicates her gastroesophageal reflux disease complains of dizziness and diarrhea. Which antacid is she most likely overusing?
Magnesium hydroxide
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?
Aluminum hydroxide; remember Aluminimumamount of feces
A patient is found to have hypophosphatemia and osetodystrophy. What medication is he most likely chronically overusing to treat his gastroesophageal reflux disease?
Aluminum hydroxide
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?
Magnesium hydroxide
What is the mechanism of action of infliximab?
It is a monoclonal antibody to tumor necrosis factor-a remember INFLIXimab INFLIX pain on TNF
List two diseases that are treated with infliximab.
Crohn’s disease and rheumatoid arthritis
What test should be conducted before starting a patient on infliximab?
Purified protein derivative test; this medication can cause reactivation tuberculosis
What are the adverse effects of infliximab?
Reactivation of latent tuberculosis, hypotension, fever
Sulfasalazine is a combination of what two drugs?
Sulfapyridine and mesalamine
What is the function of sulfapyridine?
It is an antibiotic
What unique mechanism of delivery of mesalamine is created when it is combined with sulfapyridine?
It is activated by colonic bacteria
Sulfasalazine is used to treat what two diseases?
Crohn’s disease and ulcerative colitis
What are the adverse effects of sulfasalazine?
Oligospermia, malaise, nausea, and sulfonamide toxicity
A patient is found to have Crohn’s ileitis. He asks if he can be started on sulfasalazine. What is the appropriate response?
Sulfasalazine would be ineffective because it is activated by colonic bacteria and thus has no effect proximal to the colon
Ondansetron is an antagonist of what receptor type?
5-hydroxytryptamine3
Ondansetron is used to control vomiting in which two situations?
After an operation and for patients getting cancer chemotherapy (remember: you will not vomit with ONDANSetron, so you can go ON DANCing)
What are two toxicities of ondansetron?
Headache and constipation
What is the mechanism of metoclopramide?
It is a dopamine receptor antagonist
What specific dopamine receptor is blocked by metoclopramide?
D2 receptor
With what drugs does metoclopramide interact?
Digoxin and diabetic agents
Metoclopramide is contraindicated in patients with what serious gastrointestinal disorder?
Small bowel obstruction, because it is prokinetic and thus will worsen the discomfort of these patients
On what parts of the gastrointestinal tract does metoclopramide act?
The lower esophageal sphincter (it increases tone and contractility), the stomach, and the small bowel (increases motility); it has no effect on the colon
What are the clinical uses of metoclopramide?
Diabetic gastroparesis and postsurgical gastroparesis
What are side effects of metoclopramide?
restlessness, drowsiness, fatigue, depression, nausea, diarrhea
