3. Pharmacotherapy for Acid Peptic Diseases - Pharm

• H2 blockers - MOA

  • competitively inhibit histamine on H2 receptors of gastric parietal cells
  • decrease cAMP and HCl secretion
• H2 blocker - rebound acid or hypersecretion following discontinuation
• H2 blocker name

  • ends in -tidine
• H2 blocker - adverse effects

  • neurotoxicity
  • more common in elder
  • cardiotoxicity - bradycardia + hypotension
  • thrombocytopenia
• Cime (Cimetideine) - H2 blocker - Adverse effect

  • microsomal enzyme inhibitor
  • androgen receptor blocker
  • long term use can lead to reduce sperm count
  • man boobs
• Cime - can inhibit cyp450 enzyme

  • increase serum levels of other drugs = toxicity
• Antacid decrease bioavailability of cime
• Proton-pump inhibitor (PPI) name?

  end in -prazole
• Proton-pump inhibitor (PPI) MOA

  • proton pump is the final step in secretion of HCl acid into gastric lumen from parietal cells
  • PPI are prodrug - activated and inhibit proton pumps
  • overall - inhibit secretion of acid
• PPI are prodrugs need to be activated by protonation to sulfonamide
• PPI reduce both basal and meal stimulated HCl acid secretion

  • acid-labile drugs - so food delay absorption
• PPI are preferred in zollinger ellison syndrome
• PPI works better than H2 blocker in healing peptic ulcers
• PPI long term use

  • hypochlorhydria (favors growth of bacteria)
  • leads to atrophic gastritis
  • increase the risk of pneumonia C. difficile colitis
• PPI long term use can cause

  • deficiency in iron and B12
  • increase osteoporosis - due to decrease calcium absorption
  • hypomagnesemia
• antimuscarinic drugs MOA

  • decrease gastric acid secretion by inhibition of
  • ACh
  • gastrin
  • histamine
• Scopolamine - antimuscarinic

  • use for
  • decrease gastric acid secretion
  • motion sickness
  • ADE - atropine sickness
• Miso (misoprostol) - PGE1 analog

  • MOA - increase mucus and bicarbonate production
  • prevent NSAID induced ulcers
• Bismuth MOA

  • protect ulcers from acid and pepsin
  • increase PGE2 secretion - increase mucus and bicarbonate secretion
  • inhibit pepsin
• Bismuth ADE

  • black stool
  • stain tongue black
• Bismuth is used in quadruple therapy to heal H. pylori infection
• Antacid - aluminum hydroxide

  • cause delay in gastric emptying + constipation
  • binds to phosphate and prevent its absorption --> result in decrease in phosphate
• Antacid - sodium bicarbone

  • CO2 release can cause - perforation of ulcers
• antacid sodium bicarbonate - Milk-alkali syndrome

  • if use with dairy products
  • triad
  • increase ca2+
  • metabolic alkalosis
  • acute kidney injury
• Sodium bicarbonate can lead to

  • pancreatitis
  • acute renal failure
  • ** NO use long term
• Aluminum hydroxide - use

  • hyper phosphate
  • phosphate stones
• aluminum hydroxide can lead to renal failure due to aluminum toxicity
• magnesium hydroxide

  • rapid onset
  • magnesium - enhance Gi smooth muscle contraction
  • enhance gastric emptying
  • in GIT act as osmotic purgative
  • induces diarrhea
• Calcium carbonate

  • rapid acting acid neutralizer
  • can suddenly raise the gastric pH
  • due to release of gastrin --> leading to acid rebound
• Calcium carbonate - toxicity - cause milk alkali syndrome

  • when use with milk
• Magnesium salt cause diarrhea
• Aluminum cause constipation
• All antacid may affect absorption of other medication

  • calcium + magnesium binds to drugs - reducing their absorption
  • should not be given within 2 hours after
  • such as
  • tetracyclines
  • fluoroquinolones
  • itraconazole
  • iron salt
• Anti H. pylori - triple therapy

  • two antibiotic
  • one proton pump inhibitor
  • for pt allergic to penicillin - use metronidazole
  • continue for 4-6 weeks
• Anti H pylori - quadruple therapy

  • PPI
  • bismuth
  • metronidazole
  • tetracyclines