GI drugs

Question 1

H2 blockers: Ranitidine, Cimetidine, Famotidine, Nizatidinen

Answer 1

Sketchy: Tie-dye kids = “-tidine” MOA: Reversible block of H2 receptors, which usually upregulate the H+/K+ ATPase of the apical membrane EFFECTS: Decrease of H+ secretion by parietal cells USES: Peptic ulcers Gastritis GERD (but PPIs are first line) ADVERSE EFFECTS: Increased prolactin Gynecomastia Impotence Inhibitor of CYP450

Question 2

PPIs: Omeprazole, Lansoprazole, Rabeprazole

Answer 2

Sketchy: “-azoles” = prizes MOA: Irreversible inhibits H+/K+ ATPase EFFECTS: Blocks acid production in response to all 3 stimuli: histamine, gastrin, and vagal stimulation USES: Peptic ulcers Gastritis GERD Zollinger-Ellison syndrome H. Pylori ADVERSE EFFECTS: C. Diff Pneumonia Decreases Mg2+ (require acidic environment for absorption)

Question 3

Aluminum hydroxide

Answer 3

Sketchy: None MOA: Antacid ADVERSE EFFECTS: Hypokalemia Constipation (alu-minimum amount of feces) hypophosphatemia Muscle weakness Osteodystrophy Seizure

Question 4

Calcium carbonate

Answer 4

Sketchy: None MOA: Antacid ADVERSE EFFECTS: Hypokalemia Hypercalcemia (milk-alkali syndrome) Increased rebound acid

Question 5

Magnesium hydroxide

Answer 5

Sketchy: None MOA: Antacid ADVERSE EFFECTS: Hypokalemia Diarrhea (Mg2+ must go to the bathroom) Hyporeflexia Hypotension Cardiac arrest

Question 6

Bismuth

Answer 6

Sketchy: None MOA: Binds to ulcer base, providing physical protection and allowing HCO3- secretion to reestablish pH gradient in the mucus layer USES: Increased ulcer healing Traveler’s diarrhea

Question 7

Misoprostol

Answer 7

Sketchy: None MOA: PGE analog EFFECTS: Increases production and secretion of gastric mucus barrier Decreases gastric acid production USES: - Prevention of NSAID-induced ulcers (NSAIDs block PGE production) - Maintenance of a patent ductus arteriosus - Induction of labor (ripens the cervix) ADVERSE EFFECTS: Diarrhea Contraindicated in women of child-bearing potential (abortifacient)

Question 8

Octreotide

Answer 8

Sketchy: stop sign MOA: Somatostatin analog EFFECTS: Inhibits the secretion of various hormones (e.g. inhibits histamine production from ECLs and gastrin production from G-cells) USES: Acute variceal bleeds Acromegaly VIPoma Carcinoid tumor Gastrinomas ADVERSE EFFECTS: Nausea, cramps, steatorrhea, increased risk of cholelithiasis due to CCK inhibition

Question 9

Magnesium hydroxide

Answer 9

Sketchy: magnesium bubble bath MOA: Osmotic laxative EFFECTS: Non-absorbable substance that draws water into the lumen USES: Constipation ADVERSE EFFECTS: Diarrhea Dehydration

Question 10

Polyethylene glycol (PEG)

Answer 10

Sketchy: PEG plug in floor drain MOA: Osmotic laxative EFFECTS: Non-absorbable substance that draws water into the lumen USES: Constipation ADVERSE EFFECTS: Diarrhea Dehydration

Question 11

Lactulose

Answer 11

Sketchy: Relaxulose soap being poured into the bath MOA: Osmotic laxative EFFECTS: Non-absorbable substance that draws water into the lumen USES: Constipation *Hepatic encephalopathy (gut flora degrade lactulose into acidic metabolites, which can convert toxic NH3 into NH4+ to be trapped in the lumen and excreted - prevent ammonia toxicity in the brain) ADVERSE EFFECTS: Diarrhea Dehydration

Question 12

Psyllium

Answer 12

Sketchy: bulky seaweed MOA: Bulk-forming laxative EFFECTS: Is an indigestible hydrophilic colloid; will absorb water, leading to distension and and peristalsis (pushing out everything in the bowel) USES: Constipation ADVERSE EFFECTS: Increased bloating and flatulence

Question 13

Docusate

Answer 13

Sketchy: docked boat MOA: Stool softener EFFECTS: Surfactant agent that facilitates the penetration of stool by water and lipids USES: Constipation

Question 14

Senna

Answer 14

Sketchy: Stimulating senna suntan lotion MOA: Stimulant laxative EFFECTS: Directly stimulates the enteric nervous system USES: Constipation

Question 15

Sulfasalazine

Answer 15

Sketchy: None MOA: Combination of sulfapyridine (antibacterial) and 5-ASA (anti-inflammatory); activated by colonic bacteria USES: Ulcerative colitis; Crohn disease ADVERSE EFFECTS: Malaise Nausea Sulfonamide toxicity Reversible oligospermia

Question 16

Loperamide

Answer 16

Sketchy: lop-earred rabbit MOA: Mu-opioid agonist with minimal CNS effects EFFECTS: Increases colonic phasic segmenting activity (increases colonic transmit time, thus increasing water reabsorption) USES: Diarrhea ADVERSE EFFECTS: Constipation Nausea

Question 17

Diphenoxylate

Answer 17

Sketchy: 2 dolphins fountain MOA: Mu-opioid agonist with some CNS effects EFFECTS: Increases colonic phasic segmenting activity (increases colonic transmit time, thus increasing water reabsorption) USES: Diarrhea ADVERSE EFFECTS: Constipation Nausea Treat with atropine to prevent abuse

Question 18

Ondansetron

Answer 18

Sketchy: dancer MOA: 5-HT3 antagonist EFFECTS: Decreases vagal stimulation to the medullary vomiting center produced by serotonin USES: Nausea and vomiting (postoperatively and chemo) ADVERSE EFFECTS: HA Constipation Prolonged QT interval (torsades)

Question 19

Metoclopramide

Answer 19

Sketchy: Tickler blocking the D2 rings MOA: D2 receptor antagonist EFFECTS: Upper GI prokinetic effect: Increases resting tone, contractility, LES tone, motility USES: Antiemetic Delayed gastric emptying ADVERSE EFFECTS: Diarrhea Drowsiness Depression Extra-pyramidal effects (dystonia, akathisia, parkinson’s features) Tardive dyskinesia Contraindicated in small bowel obstruction and Parkinons

Question 20

Orlistat

Answer 20

Sketchy: None MOA: Inhibits gastric and pancreatic lipase EFFECTS: Decreased breakdown and absorption of dietary fats USES: Weight loss ADVERSE EFFECTS: Steatorrhea Decreased absorption of fat soluble vitamins

Question 21

Ursodiol (ursodeoxycholic acid)

Answer 21

Sketchy: None MOA: Nontoxic bile acid EFFECTS: Increased bile secretion; decreased cholesterol secretion and reabsorption USES: Primary biliary cirrhosis Gallstone prevention or dissolution