PUD gastritis esophageal reflux / GERD Zollinger-Ellison syndrome

INCREASE risk of C. difficile infection, pneumonia (short term?) DECREASE serum Mg2+ with long term use

Gastrointestinal Pharmacology Flashcards by Hoang Tran

Examples of H2 blockers

-dine

Cimetidine

ranitidine

famotidine

nizatidine

“Take H2 blockers before you dine. Think ‘table for 2’ to remember H2.”

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H2 blockers: MOA

Reversible block of histamine H2 receptors –> DECREASE H+ secretion by parietal cells

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H2 blockers: INDICATIONS

peptic ulcer
gastritis
mild esophageal reflux

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Cimetidine--TOXICITY

(H2 blocker)

potent inhibitor of cytochrome P-450
antiandrogenic effects - prolactin release, gynecomastia, impotence, dec libido in males
can cross BBB –> confusion, dizziness, headaches
can cross the placenta - Contraindicated in pregnancy and breastfeeding?

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name the proton pump inhibitors

Examples of PPIs

-praZOLE

omeprazole

lansoprazole

esomeprazole

pantoprazole

dexlansoprazole

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PPIs: MOA

Irreversibly inhibit H+/K+ ATPase in stomach parietal cells

(unlike H2 blocker which is a reversible block of histamine H2 receptor and indirectly affect the parietal cells)

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PPIs: INDICATIONS

PUD
gastritis
esophageal reflux / GERD
Zollinger-Ellison syndrome

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PPIs - toxicity

INCREASE risk of C. difficile infection, pneumonia (short term?)
DECREASE serum Mg2+ with long term use

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How does antacid usage affect other drugs?

Antacids: Drug Interactions

Affect absorption, bioavailability, or urinary excretion of other drugs by

altering gastric and urinary pH or
by delaying gastric emptying

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name 3 types of antacids

aluminum hydroxide
calcium carbonate
magnesium hydroxide

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what can all antacids cause?

HYPOKALEMIA

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aluminum hydroxide–toxicity

contipation
hypophosphatemia
proximal muscle weakness
osteodystrophy
seizures

“Aluminimum amount of feces”

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calcium carbonate–toxicity

hypercalcemia–milk alkali syndrome
rebound acid increases
can chelate and decrease effectiveness of other drugs (ie. tetracycline)

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magnesium hydroxide–toxicity

diarrhea

hyporeflexia

hypotension

cardiac arrest

“Mg2+ = Must go to the bathroom”

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bismuth, sucralfate–mechanism

bind to ulcer base which protects it and allows HCO3- secretion to reestablish pH gradient in the mucous layer

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bismuth, sucralfate–use

inc ulcer healing

travelers’ diarrhea

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misoprostol–mechanism

a PGE1 analog

inc production and secretion of gastric mucous barrier

dec acid production

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misoprostol–use

prevention of NSAID induced peptic ulcers (NSAIDs block PGE1 production)

maintenance of a patent ductus arteriosis

also used off label for induction of labor–ripens cervix

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misoprostol–toxicity

diarrhea

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contraindication for misoprostol

women of childbearing potential (abortifacient)

name the stimulant laxatives

Bisacodyl (DULCOLAX)

Senna (SENOKOT)

Castor Oil

Examples of saline laxatives

Magnesium hydroxide (MILK OF MAGNESIA)

Magnesium sulfate (EPSOM SALTS)

Magnesium citrate

Sodium phosphate (FLEET’S PHOSPHOSODA)

Saline laxative MOA

draw water into the intestinal lumen

name the osmotic laxatives

magnesium hydroxide

magnesium citrate

polyethylene glycol

lactulose

osmotic laxatives--mechanism

provide osmotic load to draw water into the GI lumen

osmotic laxatives--use

constipation

lactulose--use and specific mechanism

(osmotic laxative) helps treat hepatic encephalopathy since gut flora degrade it into metabolites (lactic acid and acetic acid) that promote nitrogen excretion as NH4+

osmotic laxatives--toxicity

diarrhea dehydration may be abused by bulimics

sulfasalazine--mechanism

combination of sulfapyridine (antibacterial) and 5-aminosalicyclic acid (anti-inflammatory) activated by colonic bacteria

sulfasalazine--use

ulcerative colitis Crohn disease (colitis component)

sulfasalazine--toxicity

malaise nausea sulfonamide toxicity reversible oligospermia

loperamide--mechanism

agonist at mu-opioid receptors slows gut motility poor CNS penetration (low addictive potential)

loperamide--use

diarrhea

loperamide--toxicity

constipation nausea

ondansetron--mechanism

5-HT3 antagonist decrease vagal stimulation powerful central acting antiemetic

ondansetron--use

control vomiting postop and in patients undergoing cancer chemotherapy "at a party but feeling queasy? Keep **on danc**ing with **ondans**etron"

ondansetron--toxicity

headache constipation QT interval prolongation

metoclopramide--mechanism

D2 receptor antagonist inc resting tone, contractility, LES tone, motility does not influence colon transport time

metoclopramide--use

diabetic and postsurgery gastroparesis antiemetic

metoclopramide--toxicity

inc Parkinsonian effects, tardive dyskinesia restlessness drowsiness fatigue depression diarrhea

what is a possible drug interaction with metoclopramide?

digoxin diabetic agents

what is a contraindication for metoclopramide?

patients with small bowerl obstruction or Parkison disease (due to D2 receptor blockade)

What drugs/classes of drugs can lower lower esophageal sphingter tone increasing risk of reflux?

Anticholinergics Benzodiazepines Caffeine CCB (dihydropyridines) Estrogen/progesterone Nicotine Nitrates Theophylline TCAs

What is important patient teaching when prescribing a PPI?

uDo not crush or chew capsules uTake before meals – preferably breakfast uLong term users (\>6 months) need to taper off uRebound gastric hypersecretion is common

which class of anti-emetics is most frequently prescribed for motion sickness?

anticholingerics/antihistamines

ursodiol (ursodeoxycholic acid)--mechanism

non toxic bile acid inc bile secretion dec cholesterol secretion and reabsorption

ursodiol (ursodeoxycholic acid)--use

primary biliary cirrhosis gallstone prevention or dissolution

Common side effects of phenothiazines (compazine and phenergan)

Blurred vision, Dry mouth, Dizziness, Restlessness, Seizures, **Extrapyramidal effects - Tardive dyskinesia** (long term treatment)