Pharmacology

Question 1

Mechanism of action of Methylnaltrexone

Answer 1

μ-opioid receptor antagonist that reverses antiperistaltic effects of opiates. Doesnt cross BBB so doesnt induce opiate-related withdrawal symptoms.

Question 2

Clinical manifestations of Carcinoid syndrome

Answer 2

Flushing, asthma-like symptoms (wheezing, dyspnea), diarrhea, syncope (due hyotension). Also right-sided valvular heart disease and pellagra.

Question 3

Mechanism of action of Ocreotide

Answer 3

Synthetic analog of somatostatin with a longer half-life. Inhibits secretion of many hormones and hormone-like substances.

Question 4

Mechanism of action of Polyethylene glycol

Answer 4

Osmotic laxative. Promotes osmotic load to draw water into GI lumen

Question 5

Mechanism of action of Ondansetron

Answer 5

5-HT3 antagonist. Useful in the treatment of visceral nausea due to GI insults.

Question 6

Mechanism of action of Stimulants laxatives (Senna, Bisacodyl)

Answer 6

Enteric nerve stimulation → colonic contraction

Question 7

Mechanism of action of Rifaximin

Answer 7

Decreases intraluminal ammonia production by gut bacteria

Question 8

Mechanism of action of Lactulose

Answer 8

Increases conversion of ammonia (NH3) to ammonium ion (NH4)

Question 9

Mechanism of action of Loperamide and Diphenoxylate

Answer 9

Agonist at μ-opioid receptors, inhibits release of ACh. Slows gut motility

Question 10

Pathway through ECL cells increase secretion of HCl

Answer 10

Release histamine which binds H2 receptors on basolateral parietal cell

Question 11

Pathway through vagal stimulation increases secretion of HCl

Answer 11

Release ACh which binds muscarinic M3 receptors on parietal cell.
Also promotes secretion of gastrine releasing peptide which stimulates gastrin release from G cells.

Question 12

Pathway through protein rich meals increase secretion of HCl

Answer 12

Stimulation of G cells to release of gastrin which binds CCKb receptor either on ECL cell or parietal cells

Question 13

Clinical manifestations of Wilson disease

Answer 13

Onset before 40yo with liver disease (↑ transaminases, hepatitis, acute liver failure, cirrhosis), neurologic disease (tremor, parkinsonism), psychiatric disease, hemolytic anemia, renal disease and Kayser-Fleischer rings

Question 14

Molecule that promotes intestinal inflammation by inducing lymphocyte proliferation in Crohn disease

Answer 14

TNF α

Question 15

Triple therapy for H. pylori erradication

Answer 15

Amoxicillin (metronidazole if penicillin allergy) + Clarithromycin + PPI.
Quadruple therapy with bismute subsalicylate

Question 16

Desired effects of Spironolactone in the treatment of ascities

Answer 16

Natriuresis without blocking vasoconstrictive effects of aldosterone

Question 17

Motility disorder characterized by absence of esophageal peristalsis in distal esophagus and incomplete relaxation of LES

Answer 17

Achalasia

Question 18

Treatment of achalasia

Answer 18

Injection of botulinum toxin into LES, leading to sphincter relaxation

Question 19

Deficiencies found following gastrojejunostomy

Answer 19

Thiamine, folate, vit B12, iron, calcium, fat-soluble vit