Gastrointestinal Flashcards
H2 blockers
"-dine" Cimetidine Ranitidine Famotidine Nizatidine
Reversible block of histamine H2 receptors = decreased H+ secretion by parietal cells
Cimetidine toxicity
Potent inhibitor of cytochrome P450 (multiple drug interactions)
Antiandrogenic effects (prolactin release, gynecomastia, impotence, decreased libido in males)
Can cross BBB (confusion, dizziness, headaches) and placenta
Decrease renal excretion of creatinine (also seen with ranitidine)
Proton pump inhibitors
"-prazole" Omeprazole Lansoprazole Esomeprazole Pantoprazole Dexlansoprazole
Irreversible inhibit H+/K+ ATPase in stomach parietal cells
PPI toxicity
Increased risk of C. difficile infection and pneumonia
Hip fractures and decreased serum Mg2+ with long term use (can also affect B12 absorption)
Bismuth, sucralfate
Bind to ulcer base, providing physical protection and allowing HCO3 secretion to reestablish pH gradient in mucous layer
Misoprostol
PGE1 analog
Increases production and secretion of gastric mucous barrier
Decreases acid production
Which drug(s) is/are used to increase ulcer healing and treat travelers’ diarrhea?
Bismuth
Sucralfate
Which drug can be used to prevent NSAID induced peptic ulcers?
Misoprostol
NSAIDs block PGE1 production so treat with PGE1 analog
Which drug can be used to maintain a PDA? Induce labor?
Misoprostol
Prostaglandins keep the ductus arteriosus open
Prostaglandins “ripen” the cervix to induce labor
Misoprostol toxicity
PGE1 analog
Diarrhea
Contraindicated in women of childbearing potential (abortifacient)
Octreotide
Long-acting somatostatin analog
Which drug can be used in the treatment of acute variceal bleeds, acromegaly, VIPoma, and carcinoid tumors
Octreotide
Octreotide toxicity
Long-acting somatostatin analog
Nausea
Cramps
Steatorrhea
Antacids (3)
Aluminum hydroxide
Calcium carbonate
Magnesium hydroxide
Can affect absorption, bioavailability, or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying
All can cause HYPOkalemia
Aluminum hydroxide overuse problems
Constipation ("aluMINIMUM amount of feces")
Hypophosphatemia
Proximal muscle weakness
Osteodystrophy
SeizuresCalcium carbonate overuse problems
Hypercalcemia
Rebound acid increase
Can chelate and decrease effectiveness of other drugs (tetracyclines)
Magnesium hydroxide overuse problems
Diarrhea (Mg = “M”ust “g”o to the bathroom)
Hyporeflexia
Hypotension
Cardiac arrest
Osmotic laxatives
Magnesium hydroxide
Magnesium citrate
Polyethylene glycol
Lactulose
Provide osmotic load to draw water out
Use = constipation
Added treatment benefit of lactulose
Osmotic laxative that also treats HEPATIC ENCEPHALOPATHY since gut flora degrade it into metabolites (lactic acid and acetic acid) that promote nitrogen excretion as NH4+
Osmotic laxative toxicity
Diarrhea
Dehydration
May be abused by bulimics
Infliximab
Uses?
Monoclonal antibody to TNF-a
Use = Crohn disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriasis
Infliximab toxicity
Monoclonal AB to TNF-a
Infection (including reactivation of latent TB)
Fever
Hypotension
Sulfasalazine
Uses?
Combination of sulfapyridine (antibacterial) and 5-aminosalicylic acid (anti-inflammatory)
Activated by colonic bacteria
Use = Ulcerative colitis, Crohn disease
Sulfasalazine toxicity
Combination of sulfapyridine (antibacterial) and 5-aminosalicylic acid (anti-inflammatory)
Malaise, nausea, sulfonamide toxicity, reversible oligospermia
Ondansetron (Zofran)
5-HT3 antagonist
Decreases vagal stimulation
Powerful central-acting antiemetic
“Keep on dancing with ondansetron”
Ondansetron uses and toxicity
5-HT3 antagonist
Uses = controlling vomiting postoperatively and in patients undergoing cancer chemotherapy
Toxicity = headache, constipation
Metoclopramide
D2 receptor antagonist
Increases resting tone, contractility, LES tone, motility
Does NOT influence colon transport time
Which antiemetic can is used to treat diabetic and post-surgery gastroparesis?
Metoclopramide
Metoclopramide toxicity
D2 receptor antagonist
Increased parkinsonian effects
Restlessness, drowsiness, fatigue, depression, nausea, diarrhea
Drug interaction with digoxin and diabetic agents
Contraindicated in patients with small bowel obstruction or Parkinson disease (D1 receptor blockade)
