GI drugs Flashcards
H2 blockers (4)
Cimetidine, Ranitidine, Famotidine, Nizatidine
H2 blockers mechanism
reversible block of histamine H2 receptors leading to decreased H+ secretion by parietal cells
H2 blockers clinical use
peptic ulcer gastritis mild reflux
Cimetidine toxicity
-potent inhibitor of CYP450 -antiandrogenic effects (prolactin release, gynecomastia, impotence, decreased libido) -crosses BBB (confusion, HA) and placenta
Both Cimetidine and Ranitidine can…
decrease renal excretion of creatinine.
Proton pump inhibitors (5)
Omeprazole Lansoprazole Esomeprazole Pantoprazole Dexlansoprazole
PPI MOA
irreversibly inhibit H+/K+ ATPase in stomach parietal cells
Clinical Use of PPIs
-peptic ulcer -gastritis -reflux -ZE syndrome
Toxicity of PPIs
-C. diff infxn -pneumonia -hip fractures -decreased magnesium
Bismuth and Sucralfate MOA
bind to ulcer base, providing physical protection and allowing HCO3- secretion to reestablish pH gradient in mucous layer
Bismuth and Sucralfate Use
increases ulcer healing traveler’s diarrhea
Misoprostol mechanism
PGE1 analog that increases the production/secretion of gastric mucous barrier and decreases acid production
Misoprostol use
prevention of NSAID-induced peptic ulcers maintenance of PDA induce labor
Toxciity of Misoprostol
diarrhea
Misoprostol is contraindicated in…
women of childbearing potential because it is an abortifacient.
Octreotide MOA
long-acting somatostatin analog
Octreotide Use
-acute variceal bleeds -acromegaly -VIPoma -carcinoid tumors
Toxicity of Octreotide
nausea cramps steatorrhea
Antacid use can affect the…
absorption, bioavailablity or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying.
All antacids can cause…
hypokalemia.
Antacids (3)
- Aluminum hydroxide 2. Calcium carbonate 3. Magnesium hydroxide
Aluminum hydroxide overuse can cause…
constipation and hypophosphatemia, proximal muscle weakness, osteodystrophy and seizures
Overuse of calcium carbonate can cause…
hypercalcemia and cause a rebound acid increase.
Overuse of magnesium hydroxide can cause…
diarrhea, hyporeflexia, hypotension and cardiac arrest.
Osmotic laxatives (4)
- magnesium hydroxide 2. magnesium citrate 3. polyethylene glycol 4. lactulose
Osmotic laxative MOA
provide osmotic load to draw water out
Lactulose also helps treat hepatic encephalopathy since…
gut flora degrade it into metabolites (lactic acid and acetic acid) that promote nitrogen excretion as NH4+.
Infliximab MOA
monoclonal antibody to TNF-alpha
Infliximab clinical use
-Crohn’s -UC -RA -ankylosing spondylitis -psoriasis
Toxicity of Infliximab
-infection (including reactivation of latent TB)
Sulfasalazine MOA
combo of sulfapyridine (antibacterial) and 5-aminosalicylic acid (anti-inflammatory) activated by colonic bacteria
Uses of Sulfasalazine
-UC -Crohn’s
Toxicity of Sulfasalazine
-sulfonamide toxicity -reversible oligospermia
Ondansetron
5-HT3 antagonist (decreases vagal stimulation) powerful central-acting antiemetic
Metoclopramide MOA
D2 receptor antagonist (increases resting tone, contractility, LES tone and motility)
Use of Metoclopramide
-diabetic and post-operative gastroparesis -antiemetic
Toxicity of Metoclopramide
-increased parkinsonian effects -interaction with digoxin and diabetic agents
Metoclopramide is contraindicated in pts with…
small bowel obstruction or Parkinson disease.
