Upper GI Pharmacology Flashcards
1
Q
Antibiotics role in peptic ulcers
A
- critical role in eradicating H. pylori infection (associated w/many ulcers)
- use: reduce rate of recurrence of gastric and duodenal ulcers
- one component of “triple” or “quadruple” therapy
2
Q
Triple therapy drugs/use
A
- use: tx of H. pylori-associated ulcers
- PPI
- Clarithromycin
- Amoxicilin
- OR Metronidazole
3
Q
Quadruple therapy drugs
A
- Bismuth subsalicylate
- Metronidazole
- Tetracycline
- PPI or H2 antagonist
4
Q
Sequentioal therapy drugs
A
- Amoxicillin + PPI (5 days)
- then Clarithromycin + Tinidazole + PPI (5 days)
5
Q
Proton Pump Inhibitors: MOA
A
- administered as prodrug ==> systemic circulation ==> parietal cells ==> active sulfenamide
- covalent linkage to H+-K+-ATPase irreversible inactivates enzymes
- 18 hours req. for synthesis of new enzyme
6
Q
Examples of PPIs
A
- Omeprazole (Prilosec)
- Lansoprazole (Prevacid)
7
Q
Clinical uses of PPIs
A
- GERD
- Peptic Ulcer Disease
- NSAID-induced ulcers
- Zollinger-Ellison syndrome (symptom relief/ulcer healing)
8
Q
H2 Receptor Antagonists examples
A
- Ranitidine [Zantac]
- Cimetidine [Tagamet]
- Famotidine [Pepcid]
- Nizatidine [Axid]
9
Q
H2 Receptor Antagonist: MOA
A
- reversible, competitive block at parietal cell H2 receptors on basolateral membrane
- better @ blocking nocturnal acid secretion (H2-mediated) vs. meal-stimulated (ACh/gastrin)
- Less efficacious than PPIs but still suppress 24 hour acid secretion by 70%.
10
Q
PPIs: Pharmacokinetics/Dosing
A
- rapidly absorbed
- good oral availabilty w/enteric coating
- dosing: empty stomach 1 hour before meals
- metabolism: CYP450
11
Q
H2 Antagonists: Pharmacokinetics/Dosing
A
- rapidly absorbed from GI tract
- some enhancement w/food
- dosing: BID
- metabolism: mostly renal ==> dosage adjustment w/impaired renal fxn
12
Q
H2 antagonists: clinical uses
A
- GERD
- PPIs preferred in severe erosive esophagitis
- Peptic Ulcer Disease
- used at bedtime for noctural acid secretion
- Stress-related gastritis
13
Q
PPIs: Side effects/drug interactions
A
- mild SE (headache, ab pain, naseau)
- chronic use ==>
- hypergastrinemia
- rebound gastric acidity after discontinuation
- chronic use ==>
- drug-drug interactions
- CYP450 metabolism ==>
- omeprazole ==> inhibits conversion of clopidogrel (antiplatet agent) to active form
14
Q
H2 antagonists: Side effects/drug interactions
A
- Side effects
- rare and mild (dizzy, diarhea/constipation, HA)
- some rare CNS/endocrine effects
- drug-drug interactions
- Cimetidine inhibits cytochrome P450 oxidative metabolism ==>
- increase the effects or toxicity of number of drugs (theophylline, warfarin, phenytoin, carbamazepine, ketoconazole, itraconazole, benzodiazepines).
- All antisecretory agents can decrease ketoconazole absorption by causing an increase in gastric pH.
15
Q
Sucralfate [Carafate]: MOA
A
- = sulfated disaccharide aluminum salt
- MOA: binds to necrotic ulcer tissue form protective barrier
- used infrequently or an adjunct therapy