Gastrointestinal Flashcards
PPIs decrease acid production by around ____%
80-95%
PPI effect duration
24-48 hours
PPI ADME
A: 30 min before meal or IV
D: 95% protein binding
M: CYP2C19, CYP3A4
E: urine
PPI uses
- PUD or stress ulcers
- GERD
- Gastritis
- H.pylori or NSAID gastropathies
- Zollinger-Ellison sx
- MALT lymphoma
PPI mechanism of action
PRODRUG
Irreversible H+/K+ ATPase inhibition in parietal cells
= higher pH
PPI possible side effects
- C.difficile infection
- Decreased iron and B12 absorption
- Osteoporosis
- Pneumonia risk
PPI interactions (6)
- Clopidogrel
- Warfarin
- Diazepam
- Phenytoin
- Carbamazepine
- Nifedipine
H2 receptor antagonists (3)
- Ranitidine
- Famotidine
- Cimetidine
Ranitidine mechanism of action
H2 receptor antagonist on parietal cells
—> less cAMP —> less gastric acid secretion
Ranitidine and famotidine uses (5)
- Peptic ulcer healing
- Anaphylactic shock
- GERD
- Gastritis
- Zollinger-Ellison sx
Which are more effective: PPIs or ranitidine?
PPIs
Ranitidine and famotidine ADME
A: oral, IV, IM
D: low protein binding, cross placenta, cross BBB
M: hepatic
E: urine
Note: inhibits CYP2C19
Misoprostol mechanism of action
PGE2 analog —> mucus secretion + blood flow + inhibit acid secretion (up to 3 hours)
Which medication can be used as prophylaxis for NSAID-induced gastric ulcers?
Misoprostol
Misoprostol side effects (2) + biggest contraindication
- Diarrhea
- IBD symptom exacerbation
PREGNANCY —> contractions = abortion
Sucralfate mechanism of action
Inhibit hydrolysis of mucosal proteins by sticking to epithelial cells —> less erosion and ulcers for 6 hours
Sucralfate should not be taken with: (3 )
PPIs
H2 blocker
Aluminum containing antacids
Sucralfate ADME
A: oral minimal absorption, 1 hr before meal
D: minimal
M: HCL reaction —> sucrose sulfate
E: feces
Bismuth mechanism of action
Binds to ulcer affected mucosa —> physical protection
Stimulates gastric HCO3
Which antiulcer agent is used for H.pylori eradication and traveler’s diarrhea?
Bismuth
Bismuth most relevant side effect
Stool darkening
Bismuth ADME
A: oral
D:
M: hydrolyzed to bismuth and salicylic acid
E: urine
Mg hydroxide and Al hydroxide mechanism of action, and their difference
ANTACIDS
React with HCL —> produce low acidity salts
Mg: fast acting
Al: slow acting
Side effects of hydroxide antacids (3)
- Hypokalemia
- Bloating
- Belching
Mg: diarrhea, hyporeflexia, hypotension, cardiac arrest
Al: constipation, hypophosphatemia, osteodystrophy, proximal muscle weakness, seizures
Hydroxide antacids ADME
A: oral, 1-3 hrs after meals and before bedtime
D
M: HCL reaction
E: 30 min from stomach, 2-3 hrs from food
Difference of treatment between hemorrhagic ulcers and NSAID induced ulcers.
Hemorrhagic: IV PPI
NSAID induced: PPI, then H2 antagonist and misoprostol if needed
Stress ulcer treatment of choice
Sucralfate
IV H2 antagonists
NOT PPI
Zollinger-Ellison treatment of choice
High PPI dose, then octreotide if needed
First line GERD treatment in general population and pregnant population
PPI, then H2 antagonists if failed
Pregnancy: antacids and sucralfate, PPI only if severe
Metoclopramide mechanism of action
D2 receptor antagonist and serotonin antagonist
—> Antiemetic
—> Prokinetic ONLY UPPER GI