H2 antagonist

• Histamine receptor blockers suppress gastric acid. They are available OTC in lower dosage forms and are the most popular drug for treatment of acid related disorders
• Examples

  • cimetidine
  • famotidine (pepcid)
  • ranitidine (zantac)
• Mechanism of action: lock histamine at the H2 receptors of acid producing parietal cells

  • reduce production of hydrogen ions = decreased HCL production
  • suppress acid secretion in stomach
• Indications

  • GERD
  • PUD
  • erosive esophagitis
  • upper GI bleed (conjuct therapy)
  • pathological gastric hypersecretory conditions
• Contraindications

  • drug allergy
  • food (decreases absorption)
  • precautions: pregnancy, hepatic disease (liver), renal impairment, advanced age
• Drug interaction

  • inhibit the absorption of drugs requiring an acidic GI environment for absorption
  • smoking decreases effectiveness
• Adverse effects

  • fewer effects than other meds
  • pneumonia
  • CNS in older adults: confusion, hallucination, somnolence, restlessness