GIT Flashcards
H2 blocker
Drug names
Cimetidine, Ranitidine, Famotidine, Nizatidine
H2 blockers
MOA
Reversibly block H2-receptors – dec. H+ secretion by parietal cells.
H2 blockers
Clinical use
Peptic ulcer
Gastritis
Mild esophageal reflux
H2 blockers
Toxicity
> Cimetidine: CYP450 inhibitor, antiandrogenic, crosses BBB and placenta.
Cimetidine, ranitidine: dec. creatinine excretion.
Proton Pump Inhibitors
Drug names
Omeprazole, Lansoprazole, Esomeprazole, Pantoprazole, Dexlanzoprazole
Proton Pump Inhibitors
MOA
Irreversibly inhibit H/K ATPase in parietal cells.
Inc. gastric pH.
Proton Pump Inhibitors
Clinical use
Peptic ulcer, gastritis, esophageal reflux
Zollinger-Ellison syndrome
Proton Pump Inhibitors
Toxicity
C.difficile infection, pneumonia.
Dec. serum Mg w/ long-term use.
Octreotide
MOA
Somatostatin analog.
Inhibits splanchnic vasoconstriction hormones.
Octreotide
Clinical use
Acute variceal bleeds
Acromegaly
VIPoma, carcinoid tumors
Misoprostol
MOA
PGE1 analog.
Inc. production/secretion of gastric mucosa.
Dec. acid production.
Misoprostol
Clinical use
> Prevents NSAID-induced peptic ulcers.
Maintains PDA.
*CI in women of childbearing potential (abortifacient).
Bismuth, Sucralfate
MOA, clinical use
> Bind to peptic ulcer base – protection – allows HCO3- secretion to reestablish pH gradient in mucous layer.
For ulcer healing, traveler’s diarrhea.
Antacids
MOA, clinical use
Affect absorption, bioavailaibility, urinary excretion of other drugs – alters gastric acid and urinary pH, delays gastric emptying
Antacids
Drug names
Aluminum hydroxide
Calcium carbonate
Magnesium hydroxide
Osmotic laxatives
Drug names
Magnesium hydroxide
Magnesium citrate
Polyethylene glycol
Lactulose
Osmotic laxatives
MOA
Provide osmotic load to draw H2O into GI lumen
Osmotic laxatives (Lactulose) Clinical use
Constipation.
Treat hepatic encephalopathy.
*Lactulose degraded into lactic acid and acetic acid by gut flora – promotes nitrogen excretion (NH4+).
Metoclopramide
MOA
D2 receptor antagonist.
Inc. resting tone, contractility, LES tone, motility.
>No influence on colon transport time.
Metoclopramide
Clinical use
Diabetic and postsurgery gastroparesis.
Antiemetic
Metoclopramide
Toxicity
Inc. parkinsonian effects, tardive dyskinesia.
*CI in pts w/ small bowel obstruction, Parkinson dse (due to D1-receptor blockade).
Ondansetron (5HT3 antagonist)
[MOA, use]
Normally, 5HT released from enterochromaffin cells in response to chemotherapy drugs – stimulates vagal afferents to initiate vomiting reflex.
Odansetron blocks the action of 5HT3 in vagal terminals at GIT and receptors in CTZ.
>For controlling post-op vomiting, and for pts undergoing chemotherapy.
Sulfasalazine
[MOA, use]
> Combination of sulfapyridine (antibac) and 5-aminosalycylic acid (anti-inflam). >Activated by colonic bacteria.
For UC, CD (colitis component).
