mcp: gi Flashcards
antacids MOA
Neutralizes gastric acid in the stomach by raising gastric acid pH
H+ in lumen = gastric acid production
Neutralized by:
- Al hydroxide
- Mg2+ hydroxide
- Na+ bicarbonate
- Ca2+ carbonate
antacids indications
mild, infrequent heartburn
antacids onset of action
Rapid relief (5-15 minutes)
antacids duration of action
30 minutes – 3 hours
antacids formulations
Oral tablet/liquid, sublingual tablet
antacids precaution
- young or advanced age
- pregnant or breastfeeding women
- on potentially interacting medications, consider separation of medicines
- renally impaired
- pre-disposed to bowel obstruction
antacids precaution, potentially interacting medications
thyroid medicines, certain antibiotics, iron supplements
antacids precaution, renally impaired
aluminum or magnesium containing antacids
antacids precaution, significant PMH for pre-disposed to bowel obstruction
reduced bowel motility, opiate-induced constipation, dehydration, fluid retention (i.e. heart failure)
antacids length of use
Not meant for chronic use of longer than 2 weeks
H2RAs MOA
-Reversibly binds histamine-2 receptors on parietal cells: decr gastric acid secretion
normal pathway:
- Upregulation of stimulating G protein (Gs) increases cAMP levels
- cAMP stimulates the H+/K+ pump, stimulating gastric acid secretion
H2RAs indications
- Short-term treatment of mild-moderate heartburn
- Treatment of GERD and peptic ulcer disease for up to 12 weeks
H2RAs onset of action
Quick relief (30 minutes)
H2RAs duration of action
5 – 10 hours
H2RAs formulations
Oral tablet/capsule, oral liquid, IV solution
Cimetidine
- First prototypical H2RA approved by the FDA in 1979, from which other members of the class were developed
- Considered the most potent inhibitor of multiple liver enzymes, hepatotoxicity limits use of multiple medications cleared by the liver
- Other potential drug-disease interactions: mental status changes, renal impairment
- If you can avoid it, do it!
H2RAs administration
- May take with or without food
- Okay to take with antacids
H2RAs length of use
limit self-treatment of OTC product for 2 weeks; up to 12 weeks if prescribed
H2RAs side effects
- Headache, dizziness, fatigue, somnolence, constipation, N/V/D
- Generally well tolerated
H2RAs cautions/contraindications
- These medications will decrease activity of medications where acidic pH is required for absorption
- Pregnancy category B- generally safe
H2 receptor blocked by
Inhibited by:
- famotidine
- cimetidine
- ranitidine
PPI MOA
-decreases gastric acid secretion by irreversibly binding to and inhibiting the H+/K+ ATPase on parietal cells
- Irreversible action: body must generate new proton pumps on parietal cells
- Targets pumps that are actively secreting gastric acid
PPI indications
- persistent heartburn as frequent as >2 days per week or more than 3 months in duration
- First line treatment for GERD and peptic ulcer disease (PUD)
- Used in combination with antibiotics to treat H. pylori bacterial infection
PPI onset of action
- 2-3 hours initial; up to 4-5 days of therapy for maximum relief
- NOT for immediate relief of heartburn symptoms!