GI - Pharmacology Flashcards
Pg. 370-372 in First Aid 2014 Sections include: -GI therapy -H2 blockers -Proton pump inhibitors -Bismuth, sucralfate -Misoprostol -Octreotide -Antacid use -Osmotic laxatives -Infliximab -Sulfasalazine -Ondansetron -Metoclopramide
Give 4 examples of H2 blockers.
(1) Cimetidine (2) Ranitidine (3) Famotidine (4) Nizatidine; Think: “Take H2 blockers before you DINE.” to remember -dine & “Table for 2” to remember H2.
What is the mechanism and effect of H2 blockers?
Reversible block of histamine H2-receptors => decrease H+ secretion by parietal cells
What are 3 clinical uses for H2 blockers?
(1) Peptic ulcer (2) Gastritis (3) Mild esophageal reflux
What are 5 major toxicities to associate with H2 blockers, and to which specific H2 blocker(s) does each of these toxicities apply?
CIMETIDINE is a (1) potent inhibitor of cytochrome P-450 (multiple drug interactions); it also has (2) antiandrogenic effects (prolactin release, gynecomastia, impotence, decreased libido in males); can cross (3) blood-brain barrier (confusion, dizziness, headaches) and (4) placenta. Both CIMETIDINE and RANITIDINE (5) decrease renal excretion of creatinine. Other H2 blockers are relatively free of these effects.
What are 5 examples of Proton pump inhibitors?
(1) Omeprazole (2) Lansoprazole (3) Esomeprazole (4) Pantoprazole (5) Dexlansoprazole
What is the mechanism of proton pump inhibitors?
Irreversibly inhibit H+/K+ ATPase in stomach parietal cells
What are 4 clinical uses for proton pump inhibitors?
(1) Peptic ulcer (2) Gastritis (3) Esophageal reflux (4) Zollinger-Ellison syndrome
What are 4 toxicities to associate with Proton pump inhibitors?
(1) Increased risk of C. difficile infection, (2) pneumonia. (3) Hip fractures, (4) decreased serum Mg2+ with long-term use
What is the mechanism and effect of Bismuth? What other drug acts the same?
Bind to ulcer base, providing physical protection and allowing HCO3- secretion to reestablish pH gradient in the mucous layer; Sucralfate
What are 2 clinical uses for Bismuth, sucralfate?
(1) Increased ulcer healing (2) Traveler’s diarrhea
What are the mechanism and GI effects of Misoprostol?
A PGE1 analog. Increase production and secretion of gastric mucous barrier, Decrease acid production.
What are 3 clinical uses for Misoprostol?
(1) Prevention of NSAID-induced peptic ulcers (NSAIDs block PGE1 production); (2) maintenace of a PDA. (3) Also used to induce labor (ripens cervix)
What are 2 toxicities to associate with Misoprostol?
(1) Diarrhea. (2) Contraindicated in women of childbearing potential (abortifacient).
In what patient population is Misoprostol contraindicated, and why?
Contraindicated in women of childbearing potential (abortifacient); A PGE1 analog… used to induce labor (ripens cervix)
What is the mechanism of Octreotide?
Long-acting somatostatin analog
What are 4 clinical uses for Octreotide?
(1) Acute variceal bleeds (2) Acromegaly (3) VIPoma and (4) Carcinoid tumors
What are 3 toxicities to associate with Octreotide?
(1) Nausea (2) Cramps (3) Steatorrhea
What is the mechanism of Antacid use, and what are the effects on other drugs?
Can affect absorption, bioavailability, or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying
What toxicity can all antacids cause?
All can cause hypokalemia
What are 5 toxicities associated with overuse of Aluminium hydroxide antacid?
(1) Constipation and (2) hypophosphatemia; (3) proximal muscle weakness, (4) osteodystrophy, (5) seizures; Think: “aluMINIMUM amount of feces”
What are 3 toxicities associated with overuse of Calcium carbonate antacid?
(1) Hypercalcemia, (2) rebound acid increase; (3) Can chelate and decrease effectiveness of other drugs (e.g., tetracycline)
What are 4 toxicities associated with overuse of Magnesium hydroxide antacid?
(1) Diarrhea (2) Hyporeflexia (3) Hypotension (4) Cardiac arrest; Think: “Mg = Must Go to the bathroom”
What are 4 examples of Osmotic laxatives?
(1) Magnesium hydroxide (2) Magnesium citrate (3) Polyethylene glycol (4) Lactulose
What is the mechanism of all osmotic laxatives? Which osmotic laxative has an additional mechanism/use, and what is it?
Provide osmotic load to draw water out; Lactulose also treats hepatic encephalopathy, since gut flora degrade it into metabolite (lactic acid and acetic acid) that promote nitrogen excretion as NH4+
What is the clinical use for all osmotic laxatives? Which osmotic laxative has an additional clinical use, and what is it?
Constipation; Lactulose also treats hepatic encephalopathy
What are 3 toxicities/risks to associate with osmotic laxatives?
(1) Diarrhea, (2) dehydration; (3) may be abused by bulimics
What is the mechanism of Infliximab?
Monoclonal antibody to TNF-alpha
What are 5 clinical uses for Infliximab?
(1) Crohn disease (2) Ulcerative colitis (3) Rheumatoid arthritis (4) Ankylosing spondylitis (5) Psoriasis
What are 3 toxicities to associate with Infliximab?
(1) Infection (including reactivation of latent TB) (2) Fever (3) Hypotension
What is the mechanism of Sulfasalazine? What activates it?
A combination of sulfapyridine (antibacterial) and 5-aminosalicylic acid (anti-inflammatory). Activated by colonic bacteria.
What are 2 clinical uses for Sulfasalazine?
(1) Ulcerative colitis (2) Crohn disease
What are 4 toxicities to associate with Sulfasalazine?
(1) Malaise (2) Nausea (3) Sulfonamide toxicity (4) Reversible oligospermia
What is the mechanism of Ondansetron, and what effects does it have?
5-HT3 antagonist; decreases vagal stimulation. Powerful central-acting antiemetic; Think: “at a party feeling queasy? keep ON DANCing with ONDASentron!”
What are 2 clinical uses for Ondansetron?
Control vomiting (1) postoperatively and (2) in patients undergoing cancer chemotherapy
What are 2 toxicities to associate with Ondansetron?
(1) Headache (2) Constipation
What is the mechanism of Metoclopramide, and what effects does it have? What GI function does it not influence?
D2 receptor antagonist. Increase resting tone, contractility, LES tone, motility. Does not influence colon transport time.
What are 3 clinical uses for Metoclopramide?
(1) Diabetic and (2) post-surgery gastroparesis, (3) antiemetic
What are 10 toxicities to associate with Metoclopramide?
(1) Increase parkinsonian effects. (2) Restlessness, (3) Drowsiness, (4) Fatigue, (5) Depression, (6) Nausea, (7) Diarrhea. Drug interaction with (8) digoxin and (9) diabetic agents. (10) Contraindicated in patients with small bowel obstruction of Parkinson disease (D1-receptor blockade).
With what 2 kinds of drugs does Metoclopramide interact?
Drug interaction with digoxin and diabetic agents
In what patient population is Metoclopramide contraindicated?
Contraindicated in patients with small bowel obstruction of Parkinson disease (D1-receptor blockade).
Draw the gastric cells of the fundus and antrum, including and labeling the different inputs/structures involved in the following pharmacologic pathways: (1) Antacids (2) H2 blockers (3) Muscarinic antagonists (4) Misoprostol (5) Proton pump inhibitors (6) Sucralfate, bismuth (7) Somatostatin (octreotide).
See p. 370 in First Aid 2014 for visual
