Gastrointestinal Flashcards
(36 cards)
What are the 3 receptor types of the parietal cell that act to stimulate acid secretion through K+/H+ ATPase?
Histamine
Gastrin
Acetylcholine
What are 3 ways gastric epithelial cells protect themselves from the acidic environment?
Secrete mucus
secrete bicarb
mucosal blood flow
Which class acts to neutralize acid and promote healing in the treatment of ulcers and GERD? What are 4 agents in this class?
Antacids: Calcium carbonate (Rolaids, Tums) Sodium bicarbonate Magnesium hydroxide, magnesium carbonate (Maalox, Mylanta) Aluminum hydroxide
Which antacid is rarely used due to induced systemic alkalosis?
Sodium Bicarbonate
Which antacid agent can produce intoxication in the presence of renal disease? What agent should be used instead for pts with renal failure?
Magnesium hydroxide - Mg intoxication in renal disease
Aluminum hydroxide - useful in renal failure pts (not absorbed)
Which antacid agent can cause “rebound” acidity? What are its other adverse effects?
Calcium carbonate
–> Milk-alkali syndrome, nephrocalcinosis, digitalis antagonism, constipation
What are some adverse effects of aluminum hydroxide?
Phosphate depletion and sequelae (weakness, anemia, tetany, apnea); constipation
What are the 3 classes of agents that decrease gastric acid production?
H2 blockers
Anticholinergic agents
H+/K+ proton pump inhibitors
What are 3 anticholinergic agents that reduce acid secretion and prevent spasms? Contraindications?
Atropine sulfate
Propantheline (Pro-Banthine)
Metantheline bromide
–>Contraindications: known pyloric obstruction, hiatal hernia, or peptic esophagitis=reflux esophagitis (not used much)
Name 4 H2 blockers. Mechanism and use?
Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotidine (Pepcid)
Nizatidine (Axid)
- -> decrease basal and meal acid secretion (doesn’t need to be administered with meals)
- -> Inhibit 50-80% of 24 hour acid production
- -> Ulcer treatment; prophylactically for stress ulcers; GERD
What is a concern if Famotidine is stopped suddenly after prolonged use?
Rebound acidity
–>exaggerated response to histamine
(need to reduce dose slowly)
Cimetidine and ranitidine will do what to warfarin and lidocaine plasma levels?
increase
inhibits P450
What class of drugs will not work if taken with antacid or H2-blocker?
Proton Pump Inhibitors
require acidic environment to activate
What is the mechanism, use and side effects of Lansoprazole?
(H+/K+ ATPase inhibitor)
MECH: Non-competitive Inhibition >90% of 24 hour acid secretion (better than H2 antagonists)
USE: Ulcer treatment, H. pylori; GERD
SE: Headache, gynecomastia, gastric hyperplasia in humans and carcinoid tumors in rats long term (do not use long-term)
Which proton-pump inhibitor has the most P450 inhibition. Which has moderate? Which has NO P450 inhibition?
Most - Omeprazole
Moderate - Rabeprazol
None - Pantoprazole
What are 3 factors that impair mucosal defense?
NSAIDs;
H. pylori;
Zollinger-Ellison syndrome(↑Gastrin)
What is Sucralfate?
Sucrose Sulfate Aluminum Complex
- adjunct to ulcer treatment
- Mechanical protector –> Coats the ulcer crater to promote healing, increases mucosal resistance (requires acid environment)
[Chosen over bismuth salts since it doesn’t turn stool black]
What is the treatment for H. pylori infections?
Triple Therapy:
- PPI or ranitidine 2x a day
- plus 2 of: amoxicillin, clarithromycin, metronidazole
What is the only FDA approved drug for the prevention of NSAID induced gastric ulcers? Mechanism? Use? Contraindications?
Misoprostol (PGE2 analog)
MECH: Decrease acid production, increase mucous and bicarbonate secretion
USE: Ulcer treatment when prostaglandin production decreased (RA patients taking lots of NSAIDs)
CONTRAINDICATION: pregnancy
What is the mechanism and use of Metoclopramide and Cisapride? Which one requires special FDA approval and may cause sudden cardiac death?
MECH: Increase motor tone in lower esophageal sphincter and stomach (promotility/Dopa-blocker)
USE: GERD (w/o esophagitis), gastroparesis, Metoclopramide- anti-emetic
Cisapride- FDA approval/ sudden death (removed from market in July 2000)
What class are Prochlorperazine and Promethazine? Mechanism? Use? SE?
(Phenothiazines)- anti-emetics MECH: Prochlorperazine- Dopamine antagonist Promethazine- H1-blocker, Anticholinergic SE: Prochlorperazine- torticollis Promethazine- somnolence
What is a Benzamide derivate that has an anti-cholinergic mechanism to suppress CRTZ and is given in oral form. SE?
Tetrahydro Cannabinol (THC)
SE- munchies
CRTZ=Chemoreceptor trigger zone
What is the use, mechanism and side effect profile of Ondansetron, Granesitron & Dolasetron? Which one is safe enough for use in infants?
Anti-emetics
5HT3-blockers (serotonin antagonists)
SE: headache, dizziness, somnolence
Ondansetron- very safe
What agent would be used for gastroparesis?
Metoclopramide
taken before each meal to stimulate upper GI motility [no effect on gastric, biliary or pancreatic secretions]
