Pharm - Anti-ulcers Flashcards
list the H2- receptor antagonists
1) cimetidine
2) famotidine
3) nizatidine
4) ranitidine
list the proton-pump inhibitors
1) lansoprazole
2) dexlansoprazole
3) omeprazole
4) esomeprazole
5) pantoprazole
6) rabeprazole
list the surface acting agents
sucralfate
list the PGE1 analogs
misoprostol
list the bismuth compounds
bismuth subsalicylate
- tidine ending indicates a ______
H2 receptor antagonist
-prazole ending indicates a ______
proton pump inhibitor
MOA of histamine type 2 (H2) blockers
reversibly inhibit H2 receptors on basolateral membrane of parietal cells
- inhibits 20%-50% of acid production depending on dose
onset of action for H2 receptor blockers
rapid (0.5-2 hours)
compare onset of H2 receptor blockers, antacids, and PPIs
most rapid onset: antacids
middle: H2 receptor blocker
slowest onset: PPIs
how long does ulcer healing take w/ H2 receptor blockers
4-8+ weeks
normal adverse effects H2 receptor blockers
(all relatively mild, transient, and infrequent)
- nausea/diarrhea/constipation
- headaches
rare adverse effects of H2 receptor blockers, particularly cimetidine
- decreases testosterone binding to androgen receptors –> gynecomastia in men and galactorrhea in women
- neutropenia, thrombocytopenia
drug interactions of cimetidine (H2 receptor blocker)
cimetidine is the prototypical inhibitor of several CYP450 isoenzymes –> LOTS of drug-drug interactions
drug interactions of ranitidine (H2 receptor blocker)
inhibits CYP450 (but only 10% compared to cimetidine)
relative contraindications of H2 receptor blockers
pregnancy
- famotidine can be used
- only use ranitidine if necessary
MOA of proton pump inhibitors
covalently bind to sulfhydryl groups of H+/K+ ATPase at parietal cell secretory sites –> inhibits gastric acid secretion by irreversibly inhibiting functioning “-ase” pumps
- inhibits 50%-90% acid secretion
how long does ulcer healing take w/ PPIs
4-8+ weeks
how long does it take to see full symptom effects of PPIs and how long do their effects last
several days
- effects last 24 hours
adverse effects of PPIs
- diarrhea/dyspepsia/nausea
- CDAD** (c. diff associated diarrhea)
- headaches/dizziness
- myalgia/fatigue/myopathy
drug interactions of PPIs
omeprazole is the prototypical PPI that inhibits CYP450 –> lots of drug interactions
relative contraindications of PPIs
pregnancy
- pantoprazole can be used
- lansoprazole only if necessary
- try to avoid omeprazole
MOA of sucralfate
undergoes cross-linking from interaction w/ stomach acid –> creates a viscous, sticky polymer which adheres to epithelial cells around the ulcer’s crater –> prevents acid access to ulcer sites
may also:
stimulate local prostaglandin and mucous production and EGF (cytoprotection)
does sucralfate affect pH
nope
indications for sucralfate
duodenal ulcers, but also:
- aphthous ulcers
- mucositis/stomatitis
- radiation proctitis/ulcers (enema)
- bile reflux gastropathy
adverse effects sucralfate
constipation
relative contraindications sucralfate
severe renal failure
when should patients take sucralfate to avoid drug interactions
take 2 hours after other medications
normal frequency for taking sucralfate for active ulcers
QID
MOA misoprostol
it’s a prostaglandin E1 analog
- provides protective prostaglandin to the gastric mucosa and reduces gastric acid release from the parietal cells
- also provides cytoprotection
how does misoprostol provide cytoprotection
increases mucosal defenses
- stimulates bicarbonate and mucous production
- increases mucosa blood flow
normal indications for misoprostol
prevention of NSAID-induced gastric ulceration in patients at high risk of ulcerations and complications
off-label uses for misoprostol
- w/ or w/o mifepristone for pregnancy termination
- alone for cervical ripening
- post-partum hemorrhaging
adverse effects misoprostol
- diarrhea
- headaches/dizziness
contraindications for misoprostol
- pregnancy (unless specifically for common, off label issues)
- IBD
MOA bismuth compounds
believed to prevent microbial attachment to mucosa, possible inactivation of enterotoxins, and disruption of bacterial cell wall
compare uses of OTC and Rx bismuth compounds
OTC: used alone for reflux, indigestion, and diarrhea
Rx: used in combination w/ antibiotics and acid suppressants for H. pylori
adverse effects bismuth compounds
- constipation
- black/dark stools
when should patients take bismuth compounds to avoid drug interactions
2 hours after other meds
relative contraindications for bismuth compounds
absolute contraindications for bismuth compounds
relative:
- antiplatelets and anticoags
- severe renal failure
absolute:
- GI bleeding
- salicylate hypersensitivity
what is important when treating for H. pylori
COMBINATION THERAPY :)
- at least 2 antibiotics and an acid reducer (PPI or H2 blocker)
- ACG recommendations
- double therapy
- triple therapy
describe triple therapy for treatment of H. pylori
duration: 14 days
- all at BID dosing
- PPI
- clarithromycin
- amoxicillin OR metronidazole
describe quadruple therapy for treatment of H. pylori
duration: 10-14 days
- PPI at BID, all others at QID
- PPI
- metronidazole
- tetracycline
- bismuth subsalicylate
official ACG recommendations for treating H. pylori
10-14 days of triple drug regimen
- PPI
- clarithromycin
- amoxicillin OR metronidazole
describe the Helidac (QID) treatment for peptic ulcer disease
- bismuth subsalicylate
- metronidazole
- tetracyline
PLUS a PPI
describe the Pylera (3 capsules QID) treatment for peptic ulcer disease
- bismuth subcitrate potassium
- metronidazole
- tetracycline
PLUS a PPI (omeprazole)
for complete healing of ulcers, what should you prescribe after 10-14 day H. pylori combo therapy
PPI therapy for several weeks
if there is failure of eradication w/ metronidazole containing triple therapy, what should be prescribed
a non-metronidazole containing quadruple therapy
how to alter treatment in H. pylori with penicillin allergy
substitute metronidazole with bismuth quadruple therapy
how to alter treatment in H. pylori with metronidazole resistance
substitute tetracycline and consider quadruple therapy w/ clarithromycin and amoxicillin
how to alter treatment in H. pylori with clarithromycin resistance
substitute either amoxicillin or tetracycline and consider bismuth quadruple therapy
treatment for pregnant patients with PUD without H. pylori
consider short course of antacids or sucralfate
- moderate sx: consider ranitidine
- severe sx: consider lansoprazole
compare treatment in patients with PUD if NSAID is required or not required
NSAID not required: acetaminophen and discontinue NSAID
NSAID required: COX-2 NSAID and/or PPI or misoprostol
