Foregut pharmacology Flashcards
List medical conditions in which gastric acid may play a role
Gastrointestinal reflux disease (GERD)
Benign peptic ulcers of the stomach and duodenum
Ulcers secondary to the use of NSAIDs
Ulcers due to the rare Zollinger-Ellison syndrome
Describe the mechanism of action of PPIs
Irreversibly bind to H/K ATPase on parietal cells
List side effects of PPIs
Nausea Abdominal pain Constipation Flatulence Decreased absorption of calcium and drugs that require acid C diff GI infections Bronchitis and pneumonia
List therapeutic uses of PPIs
Healing of gastric and duodenal ulcers, reduce risk of ulcers and their complications, ameliorate effects of NSAIDs, treatment of gastrinoma
What is the mechanism of action of ranitidine?
Histamine H2 receptor blocker
Inhibits acid secretion by reversibly competing with histamine H2 receptors on parietal cells
others: cimetidine, famotidine, nizatidine
H2 blockers are more effective at suppressing ______ acid secretion than PPIs
nocturnal
List side effects of H2 blockers
Rare diarrhea headache drowsiness, fatigue muscular pain constipation
Cimetidine can cause _____ in men and ____ in women
gynecomastia, galactorrhea
List therapeutic uses of H2 blockers
Dyspepsia, heartburn, uncomplicated GERD, used to tx ulcers
What is the mechanism of action of misoprostol?
Prostaglandin analog
Inhibits gastric acid production by binding to the EP3 receptor on parietal cells, has cytoprotective effects by stimulating secretion of mucin and bicarbonate and improves mucosal blood flow
What are side effects of misoprostol?
Diarrhea (great for tx of constipation)
Contraindicated in pregnancy, counsel if giving to women of childbearing age
Sucralfate binds ____ AND ______
hydrochloric acid and bile salts
What is the mechanism of action of sucralfate
Cross links and polymerizes to form a viscous liquid that adheres to ulcer crates and creates a protective barrier
May stimulate local PG and EGF production
What are side effects of sucralfate?
Constipation, aluminum poisoning if renal failure, can inhibit absorption of other drugs
_____ work fastest and their effects dissipate most quickly
Antacids
What is sucralfate?
Octasulfate of sucrose with aluminum hydroxide functional group
Used to treat ulcers
What are side effects of antacids?
Altered absorption of other drugs Alkalosis from NaHCO3 Release of CO2--> belching Nausea Abdominal distension
Antacids bind ____ and ____
hydrochloric acid and bile salts
Omeprazole interferes with the effects of _____ in some patients
clopidegrel
Cimetidine interferes with the effects of ____ in some pateints
warfarin
_____ in antacids can cause constipation, whereas _____ can cause diarrhea
aluminum= constipation magnesium= diarrhea
What is appropriate therapy for peptic ulcers
acid suppression for 8 weeks
document healing only if gastric ulcer, not duodenal
Describe helicobacter plyori treatment
PPI + amoxicillin and clarithromycin (or metronidazole)
PPI, bismuth, tetracycline, metronidazole
What is the mechanism of action of metoclopride
Facilitates release of ACh from enteric neurons: Activates 5-HT4 receptors on cholinergic neurons and acts as an antagonist at D2 receptors
Results in increased gastric motility, enhanced transit
There is a black box warning on metoclopramide for _________
neurological side effects- Parkinsons like symptoms, tardive dyskinesia
Ondansetron is a ______ antagonist that is used as an antiemetic
5-HT3 receptor antagonist
Describe the mechanism of action of ondansetron (oterhs are granisetron, dolasetron, alosetron)
5-HT3 receptor blockers, antiemetic properties
highest 5-HT3 receptor concentration in nucleus tractus solitarius of vagus nerve
What are adverse reactions to 5-HT3 receptor blockers
constipation, diarrhea, headache, and light-headedness
What is the mechanism of action of prochlorperazine
D2 blocker in the chemoreceptor trigger zone, useful in motion sickness
Useful “general purpose” anti-nausea and anti-emetics
What is the mechanism of action of promethazine and meclizine
H1 receptor blocker
acts on vestibular afferents within the brainstem, useful for motion sickness and post-operative emesis
What is the mechanism of action of scopolamine
Anticholinergic used to treat motion sickness, no role in chemotherapy induced nausea
What is the ONLY cause of reversible cyclic vomiting syndrome?
THC
Relieved by hot shower
Dronabinol is useful for _______ properties in patients receiving cancer chemotherapy for which other medications are not effective
anti-emetic
Scopolamine is a ______ that is ONLY useful for motion sickness
anticholinergic
